It’s official: incumbent Nicolas Sarkozy this week declared himself a candidate for France’s presidential election, to be held over two rounds on April 22 and May 6. Sarkozy is seeking a second five-year term but so far is trailing badly in the opinion polls behind Socialist challenger François Hollande.

There was never the slightest doubt that Sarkozy would be running, but his strategy has been to continue looking “presidential” for as long as possible and keep the actual campaign relatively short. But his failure to make up ground in the polls clearly has his advisers worried, so the launch of his candidacy has been brought on earlier than expected.

Under the fifth republic, two-term presidents have been the rule rather than the exception; centrist Valéry Giscard d’Estaing, who lost narrowly to François Mitterrand in 1981, is the only incumbent to have been defeated. But unless Sarkozy can pull something out of the hat, it looks like happening again. Since being selected as the centre-left candidate last October, Hollande has maintained a consistent lead, rarely below 55% in run-off with Sarkozy (Wikipedia has a handy summary of the polls).

The striking thing about the polls is not the size of Hollande’s lead, but its consistency. He is invariably scoring in the low-30s for the first round and high-50s for the second. It’s quite reminiscent of Australia’s federal election in 2007, where even several months out the polls barely moved, showing that voters had simply stopped listening to John Howard. Sarkozy is demonstrating a similar failure to cut through, suggesting that the official start of his campaign could be his last chance to shake things up.

This is not a good time to be in government in Europe. The drawn-out economic crisis, which at first seemed to work in favour of sitting governments (or at least those of the centre-right), is starting to exhaust the patience of the electorate. Although France’s economy is in reasonable shape, continued high unemployment and a recent credit downgrade have worked against Sarkozy. Hence such dramatic recent moves as his suggestion of a referendum to tighten the rules for unemployment benefits.

Sarkozy’s main advantage will be the electorate’s reluctance to experiment with change at a time of crisis, but the calm and rather boring persona of Hollande seems to have largely neutralised that issue.

It’s hard to imagine a socialist politician who looks less like a dangerous revolutionary. Nor is it likely that the strong backing for Sarkozy of German chancellor Angela Merkel will play particularly well with French voters.

The dynamics of the race also hurt Sarkozy. In the first round, his task is not so much to beat Hollande but to make certain of being in the top two, so as to contest the run-off two weeks later. The main threat in that regard — the only candidate who is seen to have a chance of knocking him out in the first round — is Marine Le Pen of the far-right National Front.

To eat away at her support, and also to pick up her voters in the second round, Sarkozy needs to pitch to the right in policy terms. But that risks alienating voters from the centre, which will hurt him in the battle with Hollande. Contrast with the 2007 election when the main threat came from centrist candidate François Bayrou, who therefore pushed both candidates to moderate their positions.

Le Pen’s vote appears to have been weakening over recent weeks (she is now back to the mid-teens in most polls), so there’s not much doubt that Sarkozy and Hollande will face each other in the run-off. Hollande also has trouble on his extremist wing, principally from Jean-Luc Mélenchon of the Left Front, but so far that doesn’t seem to doing him much harm.

The French president is not officially the head of government, but he is more than a ceremonial figure, and when he has (as Sarkozy does) a solid legislative majority it is he rather than the prime minister that makes most of the running. Unlike most of his predecessors, Sarkozy doesn’t seem to have perfected the knack of standing back from the fray and looking “presidential”; he is too much the political animal.

For that reason, just like John Howard, he shouldn’t be underestimated when he has his back to the wall. But to make a comeback from here is a very big task.