With François Hollande’s election on Sunday as the next president of France, the next big decision point will be the president-elect’s appointment of a candidate for prime minister.

The designee will take a primary role in the upcoming June 10 and June 17 parliamentary elections and if, as is traditional, the winning presidential candidate’s party wins those elections with a majority in the Assemblée nationale, Hollande’s designee will become the head of government.

Outgoing president Nicolas Sarkozy’s center-right Gaullist Union pour un mouvement populaire, together with affiliated groups, together hold 345 seats in the current legislature, to just 227 for the left, including just 186 seats for Hollande’s Parti socialiste.  While it is typical in France for the winning presidential candidate’s party to win the election, which comes less than a month after Hollande’s decisive victory in the presidential election, Marine Le Pen’s Front national — which won almost 19% of the vote in the first round of the presidential election — will be running very hard to win seats as well, especially given the aimless state of the now-decapitated UMP, which will be somewhat driftless without Sarkozy’s leadership.

Under France’s two-round parliamentary election system, a candidate wins over 50% of the vote in the first round (and at least 25% support of all registered voters in a precinct), he or she is elected.  If not, each candidate with over 12.5% support of all registered voters (or, alternatively, the top two vote-winners if no two candidates have received 12.5%) advances to the second round, where the candidate with the most votes is elected to parliament.

As such, Hollande’s choice will be the first important signal that he provides to France, to Germany, to the rest of Europe and to the debt market as to the direction he hopes to take the French government over the next five years.

With 2002 presidential candidate Ségolène Royal — Hollande’s former partner and the mother of his children — tipped to become the president of the Assemblée nationale if the PS wins the June election, and with one-time presidential frontrunner and former IMF chief Dominique Strauss-Kahn battling legal accusations on both sides of the Atlantic, two main candidates have emerged in the media since Hollande’s election — Martine Aubry, Hollande’s rival for the PS presidential nomination and first secretary of the PS, and Jean-Marc Ayrault, president of the PS parliamentary group in the Assemblée nationale.  In addition, former prime minister Laurent Fabius, Hollande campaign manager Pierre Moscovici, former Civil Service minister Michel Sapin and campaign communications chief Manuel Valls have also been mentioned as potential prime ministers.

So who are these potential prime ministers, how would they be received and how likely are their appointments?

Martine Aubry.  The mayor of Lille and the former minister for social affairs under prime minister Lionel Jospin from 1997 to 2000, Aubry is probably the most well-known and popular choice for Hollande.  She finished second to Hollande in the PS presidential nomination contest.  The policy with which Aubry is most associated with the 35-hour work week, which was implemented as law in 1998 during the Jospin era.  She has served as first secretary of the Parti socialiste since 2008 (succeeding Hollande, in fact) and served as the labor minister in the early 1990s during the administration of the last Socialist president, François Mitterand.  Although Aubry remains popular, with the public in general and especially among the left, the relatively disappointing first-round finish of Front de gauche presidential candidate Jean-Luc Mélenchon takes some pressure off Hollande to move to the left in advance of the June elections.

Bottom line:  In appointing as prime minister the author of the notorious 35-hour work week, Hollande would be elevating the poster child of an uncompetitive and unreformed France.  It would not be a market-friendly choice and could well trigger a revolt in French bond prices and the French stock exchange.  It would also indicate that Hollande, rather than working to modernize the French left, is digging in with a “Mitterand-era” mindset.  Alternatively, however, Aubry’s selection would unify the Parti socialiste in advance of parliamentary elections and would go far in blunting the ability of  Mélenchon and the far left to win additional seats.

Jean-Marc Ayrault.  The mayor of Nantes and the president of the Socialist parliamentary group in the Assemblée nationale since 1997, Ayrault is a former German teacher who is seen as a pragmatist.  Think of him as the French left’s answer to François Fillon.  In a world where Hollande seems assured of victory in the June elections, Ayrault, who is not the most popular choice and who has not served in a ministerial role, would clearly provide more comfort to Europe and the markets than Aubry (although note that former president Jacques Chirac appointed Dominique de Villepin as his prime minister in 2005 even though he’d never been elected to any office).  Last week, Hollande said that his potential prime minister “must know the Socialist Party well, its left-wing members of parliament and be on the best of terms with me,” all of which describes Ayrault.

Bottom line:  Ayrault feels like the natural frontrunner for the premiership.  His selection would mollify German concerns about Hollande, it would soothe markets that would otherwise be wary over an Aubry premiership, and he would not challenge Hollande’s authority.  He would be a drab campaigner in the June elections, but that seems a small price to pay for the advantages he would bring to the office.

Laurent Fabius.  The 65-year-old Fabius is clearly one of the grand lions of French politics.  But as budget minister over 30 years ago, prime minister in 1984-86 during the glory days of the Mitterand administration, and finance minister under the Jospin government from 2000 to 2002, there is a sense that Fabius is yesterday’s man.  At a time when most PS and UMP leaders supported the “yes” vote in the campaign to adopt the EU constitution, Fabius stood out as a prominent proponent of a “no” vote — and, indeed, French voters ultimately rejected the constitution.  Fabius is a favorite on the left, and his appointment as prime minister would be seen as a bold statement that Hollande intends to promote a full-throated leftist program as president.

Bottom line:  If Hollande wanted to show the world that the PS is stuck in the Mitterand era of 1980s, he could not make a better choice than Fabius.  Bonus points, in a time of crisis for European unity, for choosing the most prominent opponent of the EU constitution during the 2005 campaign.  It is very much more likely that Fabius will be rewarded with the foreign ministry.

Pierre Moscovici. Hollande’s campaign manager and the former minister for European Affairs under the Jospin government from 1997 to 2002, Moscovici would not be the most popular choice for prime minister.

Bottom line:  Moscovici is in charge of Hollande’s transition team — he may not win the top job, but he will be a key player in some role for the Hollande administration.  He may well be the least likely of the six potential candidates listed here to be appointed prime minister. 

Michel Sapin.  The mayor of Aregeton-sur-Creuse, Sapin is a chief economic adviser to Hollande — he served as finance minister from 1992 to 1993 during the Mitterand administration and as the minister of Civil Servants and Sate Reforms under Jopsin from 2000 to 2002.  He is reported to be among the more fiscally conservative voices in Hollande’s circle — skeptical of eurobonds as a solution to Europe’s ongoing debt crisis and critical of big spending programs at the domestic level.

Bottom line:  Sapin is a likelier candidate for finance minister or another economic role in Hollande’s administration.  He provides all of the baggage of appointing an old-guard, Mitterand-era prime minister without any of the panache of an Aubry or Fabius appointment. 

Manuel Valls.  The youngest of the group, Valls is actually a Barcelona native by birth — he became a naturalized French citizen 30 years ago.  An MP since 2002, he finished far behind in the PS presidential nomination contest, but is known as one of the most pro-market members of the PS.  He served as the campaign’s communications chief and is popular with voters as a potential prime minister — in a recent poll, he was ranked the most popular choice for prime minister of all candidate, except for Aubry — but he has been more widely tipped as interior minister.

Bottom line: His appointment, as prime minister, or even as finance minister, would indicate that Hollande is serious about balancing France’s budget by 2017 and that Hollande is serious about elevating a new generation of PS leadership.