PARIS—President Nicolas Sarkozy was thrust into a fight for his political survival after lagging behind Socialist candidate François Hollande in the first round of France’s presidential poll.

Voters must now choose between Mr. Sarkozy, the 57-year-old incumbent who says he has the experience and energy to steer France clear of Europe’s sovereign debt crisis, and Mr. Hollande, also 57, an affable career politician who promises a more regal, conciliatory air in the Élysée presidential palace.

One crucial question is whether Mr. Sarkozy will be able to lure the 18.0% of voters who chose far right leader Marine Le Pen. Polls show that a large portion of people who voted for Ms. Le Pen in the first round may abstain in the second round rather than vote for Mr. Sarkozy.

France’s choice has large implications for the rest of Europe. Until now, the country has conformed to Germany’s austerity recipe for tackling the crisis. But Mr. Hollande, who is favored to win the May 6 runoff, has urged his neighbors to spend more to achieve economic growth.

“My responsibility, and I know that I am being watched beyond our borders, is to reorient Europe on the path of growth and job creation,” Mr. Hollande told supporters on Sunday.

Another European development over the weekend underlined signs that more Europeans were rebelling against the frugality that has dominated the continent’s response to its sovereign debt crisis. In the Netherlands, talks over measures to slash the Dutch government’s budget deficit collapsed after seven weeks of negotiations.

Dutch Prime Minister Mark Rutte said early elections were an “obvious” outcome.

Since Greece ran into financial trouble more than two years ago, followed by Ireland and Portugal, the euro zone—led by Germany—has imposed fiscal discipline as the main response to restore the public finances of debt-laden nations. Throughout the crisis, the Netherlands has been one of the most vociferous supporters of that policy.

Although the French government frequently called for better balancing fiscal discipline and euro-zone solidarity, Mr. Sarkozy sided with German Chancellor Angela Merkel to make sure all members of the monetary union stuck to a stringent diet.

However, amid the deep spending cuts, including slashing pension benefits and civil servant pay, euro-zone countries are slowing and investors have been concerned about the ability of nations such as Spain and Italy to finance their budget deficits in the bond markets.

The Dutch economy is performing poorly and is expected to shrink this year, expanding its budget deficit and making it one of the worst performing in the euro zone.

Following the weekend political developments in France and the Netherlands, the German-inspired fiscal pact, agreed by euro-zone leaders in Brussels in December, could also be delayed or thrown into question.

In a U-turn from his earlier stance, Mr. Sarkozy has used recent campaign rallies to call for changing the course of euro-zone policies to ensure they are also designed to stimulate growth.

Analysts are divided whether the disease of big budget deficits or the current prescription of budget cuts is the major