Although we still don’t know exactly how the results of the weekend’s Italian election will turn out entirely, we know enough to say that Italy’s short-term future will be beset with gridlock.

We know that, unless there’s a major change among the final results (very unlikely at this point, but still a possibility — La Repubblica‘s latest count shows a 0.4% gap between the two major coalitions), Pier Luigi Bersani will have led his broad centrosinistra (center-left) coalition to a victory in Italy’s lower house, the 630-member Camera dei Deputati (House of Deputies).  That’s because the national vote winner of the lower house elections automatically wins at least a 54% majority of the seats in the lower house.

We know that, whatever the final result, both Bersani’s centrosinistra coalition and the centrodestra (center-right) coalition led by former prime minister Silvio Berlusconi will each hold between 110 and 120 seats or so in Italy’s upper house, the Senato, which is composed of 315 elected members and, currently, four additional ‘senators for life.’ (That’s because the majority ‘seat bonus’ is awarded to the winner of each regional vote rather than on a national basis like in the Camera dei Deputati).

It doesn’t really matter who holds the greatest number of senatorial seats, because no group or party will control enough seats in the Senato alone to form a majority government, including Bersani’s coalition.

So given Bersani’s lead in the lower house, whatever government emerges — if a government emerges — will have to include Bersani’s center-left bloc, with presumably Bersani heading the government as prime minister.  In the short term, that puts Bersani in the driver’s seat but not, perhaps, for long.

None of Bersani’s options, frankly, are very stable, for either his center-left coalition or for Italy.

Given the ongoing eurozone sovereign debt crisis, the pressure will be on Bersani and on the entirety of Italy’s political elite, which now must be said to include Beppe Grillo and the leaders of the Movimento 5 Stelle (the Five Star Movement).  Right now, Italy’s 10-year bond rate is 4.49%, much lower than the 7%-and-higher rates that led to the downfall of Berlusconi’s government in November 2011.  But that could change — and fast — if Italy’s political leadership seems unable to form a government.  Grillo and his allies are now stakeholders in ensuring that Italy doesn’t unravel.

If Bersani succeeds in forming a government at all, it will be less stable than any government in Italy’s so-called ‘second republic’ — i.e., the period from the early 1990s to the present that’s been characterized by the downfall of the former Christian Democrats during the 1992 Tangentopoli (‘bribesville’) scandal that implicated virtually all of Italy’s political elite, the emergence in 1994 of Silvio Berlusconi as the head of the mainstream Italian right, and the increasing consolidation of the mainstream Italian left through what’s now become the Partito Democratico (PD, Democratic Party).

Any Bersani-led government, at this point, will not only be less stable than Berlusconi’s governments, but even less stable than the four notoriously rocky governments of Italian prime ministers Romano Prodi, Massimo D’Alema and Giuliano Amato from 1996 to 2001 and Prodi’s short-lived and troubled return to government from 2006 to 2008.

In light of that bleak background, here are the four potential outcomes over the coming days that you should watch for:

1.  Bersani-Monti minority government

Before the election, the centrosinistra‘s declining poll support meant that much of the electorate was already preparing for the possibility that no party or coalition would win a majority in the Senato.  The most likely outcome, it was believed, was a coalition between Bersani’s centrosinistra and Monti’s centrist coalition.  Given that the most leftist members of Bersani’s coalition are already none too pleased about Bersani’s plans to mostly continue Monti’s reformist agenda, it was always uncertain whether an even more pro-reform coalition, likely to enact more tax increases and/or budget cuts, could retain the far left.

It doesn’t help that one of Bersani’s key allies, Nichi Vendola, the openly gay regional president of Puglia, and the leader of the democratic socialist Sinistra Ecologia Libertà (SEL, Left Ecology Freedom), despises Monti and his socially conservative allies, many of whom are close to the Vatican, for their disapproval of same-sex marriage.  One of Monti’s chief allies, Pier Ferdinando Casini, earlier this month compared same-sex marriage to pedophilia.

So a broad Monti-Vendola-Bersani coalition was already thought to be unstable.

Given where the senatorial projections now stand, even a combined Bersani-Monti alliance in the Senato would amount to just 129 seats, about 30 seats short of the 158 threshold for a majority.  That means an already unwieldy alliance would have to go hat-in-hand to either the Five Star Movement or to Berlusconi and his allies for support on any given legislative measure, hardly a recipe for smooth governance.

2.  Bersani-Berlusconi ‘grand coalition’

Grillo, earlier today, said that the only option was for a ‘grand coalition’ between the centrosinistra and the centrodestra.

That’s a fairly outlandish notion, however, to anyone with a passing history of Italian political history, although it would leave Grillo and his Five Star Movement as the largest opposition in Italian politics and likely to pick up even more support in the next set of elections.

In short, Italy is not Germany (where the Christian Democrats and Social Democrats formed a ‘grand coalition’ from 2005 to 2009).   Post-war German politics have largely featured a moderate consensus, and you can see that even today in the upcoming contest between German chancellor Angela Merkel and her opponent Peer Steinbrück, who once served as Merkel’s finance minister — they largely see eye-to-eye on European matters, economic policy and foreign affairs.

Not so in Italy, where ideological differences are as fraught as religion — and in many cases, politics is tied to religion.  The tradition of the Italian right still has a difficult relationship with Italy’s fascist past and is still marked by the postwar alliance among the market-friendly, socially conservative Christian Democrats, the U.S. government and the Vatican, that dominated politics for four decades.  The tradition of the Italian left still has its roots in the anti-fascist partisan struggle of Italy’s civil war and the perennial opposition of the Italian Communist Party during the post-war era.

Bersani ran largely on a staid platform of staying the course set by Monti, albeit with a greater emphasis on pro-growth measures and protecting Italians from the worst of the economic recession.  Berlusconi ran largely on a populist anti-austerity, anti-Europe, anti-Monti platform.  So it’s incredibly difficult to see how the two sides would find any common ground for a ‘grand coalition.’

3. Bersani-Grillo coalition (formally or informally)

Although Grillo has said he won’t ‘wheel or deal’ to join a coalition with either side, the key to unlocking a solution may lie in Palermo where, after a highly fragmented regional election in October 2012, a center-left minority government led by Sicily’s new regional president Rosario Crocetta governs with the outside support from legislators from the Five Star Movement.

In the Sicilian election, five major parties won between 10% and 15% of the vote, the largest share going to the Five Star Movement with 14.9%.

So there’s a chance that Bersani could find enough partners within the Five Star Movement to cobble together a working majority, although the anti-austerity, anti-corruption bent of the Five Star Movement means that Bersani might have to shift further away from the Monti-esque center and even further left.  That’s something allies like Vendola would probably welcome.

Matteo Renzi, the youthful mayor of Florence who challenged Bersani in the primary to lead the centrosinistra in November 2012, has argued for a generational sweep of Italian politics and he’s echoed many of the ‘pox-on-both-your-houses’ themes Grillo has highlighted throughout the campaign in branding both major parties as corrupt and dishonest.  He’s even expressed his admiration for Grillo, who’s long been a popular blogger and commentator on public events.

There’s some incentive for Grillo to make a deal, too.  Having captured such a strong protest vote, the Five Star Movement may not want to chance a second set of elections under the pressure of an international finance crisis — it’s plausible that many protest votes could slip back to the main parties.

Grillo himself, however, did not stand for election to the Italian parliament, and it remains to be seen just what his army of newly elected Five Star Movement legislators actually believe — nearly all of them will be first-time parliamentarians and they form a diverse bloc of legislators from both the right and left, and will be the most heterodox group, by far, in Italy’s next parliament.

It’s still a longshot, of course.  But in light of the Sicilian precedent, and given that Renzi and Vendola might well find reason to support it, a Bersani-Grillo alliance isn’t as ridiculous as you might initially think — or as Grillo himself has initially indicated.

4. New elections

It’s still a strong bet that none of the three coalitions above are attainable.  It’s an even stronger bet that none of the coalitions discussed above are sustainable for a full five-year term in parliament.  That means we’re likely to see another round of elections in Italy sooner rather than later.

The PD’s deputy secretary Enrico Letta already suggested on Monday that a brief caretaker government could implement a new election law in advance of new elections later this year.

What would that mean? It’s incredibly early to tell, though there’s some chance, I suppose, that Bersani would give way for Renzi, who would likely be able to win the majority that has eluded Bersani.  Or Bersani could run again, especially if new elections come very quickly, say, in the next month or two.

Berlusconi, too, might once again lead the coalition, or he might leave it to his longtime protege, Angelino Alfano (who Berlusconi had already anointed as his choice for prime minister in the event of an unlikely centrodestra win in the weekend’s election).

Grillo and the Five Star Movement, having demonstrated its power as a third force in Italian politics, could well improve in a new set of elections.  It could also crash and burn as Italians, having lodged their protest vote, turn back to the main parties.

It seems unlikely that Monti would subject himself to another embarrassing loss in such a short period of time but, again, there’s no way to know.  If his centrist coalition doesn’t contest any future elections, Monti seems likeliest to swing his support to the centrosinistra, which could also give them the edge they need to win a second round of elections (though it might not solve the unwieldy problems of a coalition that contains Catholic conservatives, economic reformers and gay socialists).

Coda: Italy’s upcoming presidential election

On one hand, I don’t want to get too far ahead of events; on the other hand, it’s impossible to talk about the negotiations ahead without mentioning an incredibly important puzzle piece — the election of Italy’s next president.  Current president Giorgio Napolitano is set to leave office in May as Italy’s head of state and (at age 87, he’s two years older than resigning Pope Benedict XVI) he’s said he doesn’t want a second term.  Although the Italian head of state is a largely ceremonial post, the new president will have the power to call new elections and the position provides some amount of moral authority as well.

As the Italian parliament chooses the president, there’s no real ‘campaign,’ so to speak, and it’s very difficult to project who the frontrunners are.  In 2006, no one pegged Napolitano as a frontrunner to become president.

But it could well become another chip in the poke game of negotiations over potential coalitions, and there are any number of limitless possibilities, including the option that Napolitano agrees to stay on for part or all of another seven-year term.

Monti, of course, seemed like a strong choice to succeed Napolitano just a few months ago — his presence as head of state would reassure Europeans and investor types that Italy would remain in good hands under Monti’s more abstract leadership.  That seems less likely now that he’s jumped into the fray of electoral politics — and failed.

Berlusconi’s always coveted the Italian presidency (I suspect, for reasons of ego as much as for the immunity from prosecution that the position would bring).  Given that he’s pledged not to serve as prime minister, there’s nothing to lose if he were to barter the support of his party, the Popolo della Libertà (PdL, People of Freedom), for a grand coalition in exchange for the presidency.  It seems unlikely, of course, but after the past 14 months in Italian politics, with all the high drama of an opera, nothing seems incredibly fanciful.