(CNN) -- The French presidential election has entered a crucial stage as President Nicolas Sarkozy and Socialist challenger Francois Hollande campaign in the second round run-off. What are the main themes of the election, how will the system work and who is likely to win?
How did we get here?
Ten candidates took part in the first round on April 22. With all votes counted on Monday, Francois Hollande had 28.63% support, followed by Sarkozy at 27.18%. Far-right candidate Marine Le Pen garnered 17.9% of the vote, while Jean-Luc Melenchon on the extreme left had 11.11% and centrist Francois Bayrou had 9.13%. If no one candidate scored an outright majority, the two top went through to a run-off, to be held on May 6.
What are the main issues in the election?
The economy, economy, economy. Basically, for months now the top issues have been unemployment and purchasing power. To a lesser extent -- and for some candidates, a greater extent -- immigration figures in the debate. On the extremes -- both left and right -- Europe has been an issue that relates to the economic problems. With neither candidate close to a majority, who assumes the presidency hinges on what support Sarkozy or Hollande can get from those who didn't back them in the first round.
Who is expected to win?
The polls at the moment give Hollande a lead of between 6% and 8% in the second round. The first-round results appear to be historic, and a bad sign for Sarkozy. Several high-profile Hollande supporters told CNN that a French president running for re-election has never failed to place first in the first round of the vote.
When will we know the result?
We'll know on the evening of Sunday May 6. France has a fairly accurate system of exit polling that permits the news media to call the election at the moment the polls close at 8 p.m. local time. But these are exit polls and if the race turns out to be close, the media has been known in the past to start slipping into the French conditional tense, ie. "the winner might be..."!
How much interest is there in France in the election?
That depends entirely on how much of a political junkie one is. In many ways this is one of the most interesting races in decades: a sitting president fighting for his political life is the underdog, while extremist candidates at both ends of the spectrum collected almost 30% of all the votes cast in the first round.
The issues have been thoroughly debated and one reason the extremists did so well is that voters did not perceived clear distinctions between the programs of Sarkozy and Hollande, even if the two main candidates worked hard to make their differences clear.
What implications are there for the rest of Europe?
France and Germany have been at the heart of the drive to keep the European single currency sound and Europe on course. Both Sarkozy and Hollande are committed Europeans, but if either courts the extremists at either end of the spectrum for help in winning the second round, then all bets are off.
Sarkozy, of the center-right RPR party, has been a significant figure on the European and international stages since becoming president in 2007. Under his leadership, France -- one of the five permanent members of the United Nations Security Council -- has played key roles in international hot spots such as Libya, not to mention during the pan-European debt crisis, but the domestic economy has been a prime focus of the election.
What issues may emerge in the runoffs campaign?
France is struggling in the face of sluggish economic growth and a 10% unemployment rate. Hollande generally supports "more government action to stimulate the economy" whereas Sarkozy favors policies such as lowering some taxes and possibly repealing the mandatory 35-hour limit on the work week, said Michael Leruth, who teaches a course about the election at the College of William & Mary in Virginia.
German Chancellor Angela Merkel, through spokesman Georg Streiter, has expressed her support for Sarkozy, but said she would work "closely and well with any elected French president."
Sarkozy is pressing for three debates with Hollande before the next round, accusing the Socialist of "fleeing his responsibilities" by saying he wanted only one debate.