French President Valery Giscard d'Estaing and Socialist leader Francois Mitterrand are expected to emerge as the front runners in a field of 10 candidates in the first round of voting Sunday in France's two-stage presidential election.

The two candidates who win the most votes are to run against each other two weeks later.

The record of Giscard, who is seeking a second seven-year term, has been the main campaign issue for an electorate upset about unemployment and inflation.

The other main contenders this time are Communist Party leader George Marchais and Gaullist Party leader Jacques Chirac, the mayor of Paris.

Publication of opinion polls in France is illegal in the week before the voting. But IFOP, the most established polling organization, has been circulating last-minute results to political insiders showing Giscard with 27 percent, Mitterrand 23, Marchais 19, Chirac 18 and the remaining 13 percent spread among the other six candidates.

That poll also shows Mitterrant winning the run-off with 51.5 percent of the vote. The poll showed 17 percent of the electorate of nearly 37 million undecided on the eve of the election.

In what may turn out to be Giscard's major disadvantage, about 7 million young people between 18 and 25 are eligible for the first time in a presidential election. The IFOP poll showed that a disproportionate number of Giscard's supporters are old.

It was Giscard who had the voting age lowered from 21 to 18 after he was elected in 1974. Half of the country's officially acknowledged pool of 1.7 million unemployed are in the 18 to 25 age bracket.

The president has tried to shift the focus of the campaign away from inflation and unemployment to his claims that because of his leadership, France, is today the world's third most important military power, has the world's most ambitious nuclear energy program to escape dependence on imported oil and is well on track to becoming the noncommunist world's third economic power after the United States and Japan.