The campaign for French parliamentary elections kicked off just last Monday, for what most observers believe is a formality in installing the newly inaugurated President François Hollande’s Parti socialiste as the majority of the Assemblée nationale.

French voters go to the polls this Sunday for the first of two rounds — in each parliamentary district, if no candidate wins over 50% (with at least 25% support of all registered voters in the district), each candidate that commands at least 12.5% support of all registered voters (or the top two candidates, alternatively) in the first round will advance to the second round on May 17.

In 2002, parliamentary and presidential elections were fixed so that the former follows nearly a month after the latter.  As in 2002 and 2007, it is expected that the winner of the presidential race in May will thereupon see his party win the parliamentary elections in June.

The rationale is to avoid cohabitation — the divided government that sees one party control the presidency and another party control the government, which has occurred only three times in the history of the Fifth Republic (most recently from 1997 to 2002, when Parti socialiste prime minister Lionel Jospin led the government under center-right President Jacques Chirac).  More than in most countries, the French electorate seem a bit more allergic to divided government, which should give Hollande some relief in advance of Sunday’s vote.

But there are complications this time around, which may result in a somewhat murkier result.

Wait a minute, you might say: Deposed president Nicolas Sarkozy is off licking his wounds in Morocco, leaving a decapitated center-right split between followers of outgoing prime minister François Fillon and Jean-François Copé, head of the Union pour un mouvement populaire (which, unlike the Parti socialiste, is not a decades-long party, but only the latest brand of a series of shifting vehicles of France’s center-right) — Fillon and Copé last week were already sniping at one another.

A surging Front national on the far right (and increasingly and uncomfortably encroached on the center-right and parts of the populist left as well), under Marine Le Pen, garnered nearly one out of every five votes in the first round of the presidential election and is hoping to do just as well in the legislative election.

Meanwhile, Hollande’s prime minister Jean-Marc Ayrault, seen as a prudent and moderate choice to lead France’s new government, has a 65% approval rating (higher than Hollande’s own 61% approval!), and Ayrault is already moving to reverse part of Sarkozy’s signature reform — raising the retirement age from 60 to 62 — by allowing a small subset of longtime workers to retire at 60.

How, under these conditions, could the PS possibly lose?

First and foremost, the surprisingly close presidential runoff, which saw Hollande defeat incumbent Nicolas Sarkozy by just 51.5% to 48.5%.  That’s a lot closer than polls had predicted and, indeed, closer than the margin by which Sarkozy himself won the presidency in 2007.  In 2002, of course, Chirac won over 80% of the vote in unusual circumstances — his runoff opponent was the Front national leader, Jean-Marie Le Pen.  So the 2002 and 2007 precedents are less applicable than meets the eye.

Secondly, the Parti socialiste and its allies control only 227 seats in the  Assemblée nationale, while the UMP controls 345.  So the election will require a little over one-fifth of France’s parliamentary seats to switch hands — it’s not an insurmountable task, but the gap is considerable.

Thirdly, polls show essentially a tossup between the Parti socialiste and the UMP in the first round — a recent Ipsos poll from June 2 shows the UMP taking 34% to just 32.5% for the Parti socialiste.  The Front national takes 14%, while Jean-Luc Mélenchon’s Front de gauche attracts 7%, the Greens take 6% and François Bayrou’s Mouvement démocrate wins just 3%.  That’s not as bad for the Parti socialiste as it seems — invariably, much of the split leftist vote will consolidate in the second round, when many legislative contests are narrowed to direct UMP-PS faceoffs, and especially in “triangulars” or “quadrangulars,” in which Front national candidates will continue to drag support away from UMP candidates.  Although it is likely that in some races, the Front de gauche will exceed the 12.5% first-round hurdle to make it into the second round — thereby dividing leftist voters — polls indicate the vote-splitting risk in such “triangular” or “quadrangular” contests is much more likely to be on the right, where the Front national has much more electoral strength.

Indeed, leftist support total nearly 47% in the Ipsos poll, so it’s fair to expect that the Parti socialiste and its allies (it already has an electoral pact with the Greens) will win enough seats in the second round to control parliament.

But it’s by no means a slam dunk — there’s a small, but not inconsiderable chance, that France will wake up on June 18 facing a Hollande-Fillon cohabitation.