François Hollande's victory in the second round of France's parliamentary elections on 17 June 2012 was predicable, its scale expected. A month after his election as president, his Parti Socialiste (PS) now controls France's chain of political command: presidency and government, both houses of parliament (senate and national assembly - unprecedented for the left under the fifth republic), all but two metropolitan regions, two-thirds of departments, and a majority of the major cities (starting with Paris). All they lack is the two-thirds parliamentary majority needed to amend the constitution.

Now the difficulties begin. That is understood behind the closed doors of the Elysée palace and the prime-minister's office; for if the atmosphere at the PS's headquarters and in the "pink" constituencies (especially the new ones) has still been flushed with victory, those in charge of drafting and implementing the policies of a five-year term understand well the severe challenges ahead. The atmosphere was well expressed by the new premier, Jean-Marc Ayrault, who in his brief post-election speech said: "Nothing will be easy, nothing will be given to us". Or, to quote a character in a Le Monde cartoon, "We have made no promises but we now have to fulfil them".

The Hollande-Ayrault team's refusal to make promises is a break with the pattern set by Francois Mitterrand, Jacques Chirac or Nicolas Sarkozy. Perhaps the only exception is their pledge to do away with the arrogant style and "bling" characteristic of Sarkozy's tenure (which already seems distant, even among those who had been his most faithful followers before his defeat on 6 May).

French voters are aware that their country faces hard days ahead, and they want not words but deeds. They decided to change political horses in midstream because they felt that ten years of conservative governments had led them nowhere; that, for all the fiery speeches and inflated claims (by "Sarko" in particular), debts, deficits and unemployment were all still growing. So, through four excruciating rounds of voting - two presidential (22 April-6 May) and two legislative (10 June-17 June) - they went for a "normal" president and a party which had won every local-election round since 2007.

The victory

The left's victory in the latest battle royal, grand slam or tidal wave (as the newspaper headlines have variously called it) was substantial. The PS and affiliate MPs won 302 seats (eleven more than the minimum for an absolute majority), and the left together 343 (115 MPs more than in 2007), while the UMP and affiliates won 206 of the right's total of 229. There was also an infusion of younger blood (40% of new MPs), of women (155 MPs, including 107 socialists, an overal increase from 18% to 27% since the last assembly), and of ethnic-minoroty MPs (ten in metropolitan France, from just one), all of which could add dynamism to France's stale political life.The defeat of the PS's presidential candidate in 2007 (and Hollande's former partner), Ségolène Royal, to an ex-socialist rival was one of the few sources of controversy on the left.

The PS was helped by the combination of the fifth-republic's majority-voting system and the five-year presidential term introduced in 2000. This means the French now follow their election of a president by, a few weeks later, choosing a national assembly. The reduction from seven years might look a mere technicality, but it has had deep repercussions on France's political life - for once a president has been elected, voters expect him (so far, it is always a "him") to govern and grant him a majority to do so, as with Chirac in 2002 and Sarkozy in 2007. They don't want any more "cohabitation" between a leftwing president and a conservative parliament, or vice versa. The consequences include a vote that is more rational than enthusiastic, and a foreshortening of the institutional and media cycle (so while Mitterrand and Chirac were elected on their third try, Sarkozy was elected on his first, and defeated after five years rather than given another chance - something François Hollande should keep in mind).

Yet this way of governing, even if it follows the constitution to the letter, is unhealthy and inefficient. The debate on whether parliamentary elections should be held before, after, or alongside the presidential remains open. The current schedule has had the deplorable effect of demobilising voters (43.7% of voters abstained on 17 June), who come to think that joining a polling-booth queue four times in two months is unnecessary.

In any event, in order to give their president a majority, French voters privileged the two "government parties", the PS and UMP who (with their liege partners) received 77.60% of the votes and have cornered 508 of the 577 seats in the new assembly. The fate of other parties depended on whether they were allied to either of the majors: the EELV greens and left Radicals (with the PS), and the centrists and right Radicals (with the UMP) maintained their position, but the Communist-led Left Front (with ten MPs) and the ultra-right Front National (with two) were marginalised. The FN leader Marine Le Pen lost by a whisker and the centrist François Bayrou routed. Hollande has suggested that a "dose" of proportional representation might be introduced to offer these groups a closer match between votes and seats.

It is far from bad news for the FN, however. By taking 18% of the votes at the presidential election and 13.6% in the first round of the legislative, the party has shattered the unity of Chirac and Sarkozy's UMP. Sarkozy's tactic of playing the hard-right card, which had worked so well five years ago, alienated moderate conservative voters. It also reduced to irrelevance his own hardliners in the UMP, who thought they could counter the Le Pen dynasty by playing the same xenophobic tune; half of them lost their seats, while the moderates feel disenfranchised. The bitter fight for the party leadership is now on. "Marine" has other plans: she dreams of uniting the right behind her Bleu Marine Front and sending the old UMP into oblivion.

The challenge

But all this is politics and France's house is burning. Since the presidential election, Hollande and Eyrault - lacking until now a parliamentary majority - have kept very quiet on the way they intend to fight France's economic and social crisis, industry's dramatic loss of competitiveness and its worst consequence, rising unemployment (now around 10%). They have restricted themselves to saying that they want to rebalance the books within five years while rejecting Greek- or Spanish-style austerity, as advocated by Germany's chancellor Angela Merkel.

Now they are waiting for a detailed report by the Cour des Comptes (audit office) due before the end of June 2012 to detail their policies, which will be based on raising taxes in the context of a fairer tax system and (until now an undisclosed and far more painful choice) an unavoidable slashing of bloated state expenditures. To have these measures passed by parliament and rapidly implemented will be difficult.

Hollande's early approach has been broadly criticised for its lack of Churchillian style - a reversal of the praise given to him as a candidate who preferred modesty to flamboyance. The criticism seems misconceived: Hollande is not a "blood, sweat and tears" type but a gradualist who is aware of the danger of too-painful reforms in a country where people can easily mobilise in the streets (as shown by his lowering of the retirement age to 60, which is limited to those 100,000 or so who started working at a young age and completed forty-one years in employment).

Hollande believes there is an alternative to the wage-reducing, welfare-slashing response to the present crisis - left-wing, more socially friendly, but also strict on debt and deficits, and capable of improving the European Union's competitiveness. For him, public debt (brought close to 90% of GDP under Sarkozy) and budget deficits can only be reduced by "growth", the new president's mantra. This core emphasis, reflected in proposals sent to Berlin and Brussels for long-term (and long-overdue) economic and political reforms of the EU, explains his semi-public disagreements with Merkel. The daily newspaper Libération catches the mood with its headline on 19 June: "Can the left beat the crisis?", illustrated with Hollande dressed as Superman.

But neither is Hollande a dogmatic socialist of the kind long characterstic of the PS; rather he is open in claiming the term social-democrat, once anathema in the party. If this puts him at odds with more radical comrades, including at the top of the party, his absolute majority should help him to resist pressure from them as well as from the Left Front and its fiery leader Jean-Luc Mélenchon (now reduced to the status of a member of the European parliament). It should also give him the weight to strengthen his influence within the EU. For Hollande, as well as being one of Europe's few leftwing leaders, is also the most powerful domestically, has won an election most decisively, has most popular legitimacy, and can look forward to a five-year term. By contrast, Angela Merkel lacks the votes to ratify the latest European treaty - which Hollande wants amended - and will face Germany's voters in 2013.

But for Hollande to succeed, and to talk once again on equal terms with a powerful and successful Germany, he will have to offer strong leadership, outline a clear vision for France, and turn his penchant for compromise (sometimes taken as a sign of weakness) into an advantage. If he fails, France could be next in the line of countries in crisis, after Spain and Italy. The stakes are very high, for France and for Europe alike.