French President Nicolas Sarkozy moved closer to Socialist election frontrunner Francois Hollande in an opinion poll published on Tuesday, two weeks after he formally entered the race for April's presidential vote.

Several surveys of voters' intentions for the first-round ballot on April 22 show Sarkozy, who has battled bleak popularity ratings and economic gloom, gaining on Hollande since he began campaigning in mid-February.

The challenger, who on Monday proposed a new 75-percent income tax on millionaires, remains far ahead of Sarkozy in polls of how people would vote in the likely head-to-head runoff between the two men on May 6. But Sarkozy's camp hopes a strong first-round showing can change minds before the decisive day.

Tuesday's survey by Ifop/Logica Business Consulting showed that Sarkozy narrowed the first-round gap to 4.5 percentage points from 7 points a week earlier, with 27 percent support to Hollande's 31.5 percent, versus 25 and 32 percent in the pollster's previous sounding.

The same survey, carried out on February 24-25, showed Hollande 16 points ahead of Sarkozy in a runoff, at 58 percent to 42 percent. But that, too, marked a slip of one point for the Socialist and a one-point gain for Sarkozy, a conservative.

The poll of 959 people found that 22 percent of respondents could still change their minds for the second round, which will be held if no candidate wins an absolute majority in the first.

The election is a clear two-horse race, with Sarkozy selling himself as a strong pair of hands to pull France through economic turmoil with structural reforms, whereas Hollande, who is more widely liked but lacks ministerial experience, would hike wealth taxes to invest in education and jobs.

Far-right leader Marine Le Pen and centrist Francois Bayrou are both more than 10 points behind in polls for the first round. Their supporters will be key for round two. Several other candidates from minor parties will also take part.

Tax and education
On the campaign trail in the southern city of Montpellier, Sarkozy took on one of Hollande's central proposals, which is to increase the number of teachers by 60,000 over the five years of the next presidential term.

The president proposed to hike the pay of workers who agree to work longer hours by 25 percent rather than increasing their numbers, tying in with one of his main themes, that people should be rewarded with better pay when they work more.

"I believe in paying more to those who work more. I believe in the choice of rewarding talent. Rewarding merit and valuing success are principles that have always been dear to the Republic," he told a rally of supporters.

"The folly of tax policies that discourages work, that discourages initiative, isolates France from the rest of the world," Sarkozy added in an oblique attack against Hollande's latest proposal.

On Monday evening, Hollande told a television talk show that annual incomes above 1 million euros ($1.34 million) would be taxed at 75 percent if he wins, as he pounded home the idea of a fairer economy for the lower and middle classes. The current top rate of income tax, paid by many, is 45 percent.

A centre-leftist who must nonetheless rally left-wingers of all stripes behind him, Hollande has taken aim at bankers in a campaign marked by joblessness and anxiety over purchasing power. His plans to raise taxes on companies and the rich have sparked talk of an exodus from France.

Sarkozy's Finance Minister Francois Baroin slammed the idea of a 75-percent income tax rate in a debate with Hollande's campaign chief Pierre Moscovici, who said he stood by the plan.

Foreign Minister Alain Juppe told RTL radio the proposal showed Hollande was "scrambling to catch up" with Sarkozy's campaign rhythm. "He tries a new tax every day," he said.

Hollande, who laid out his program a month ago, decried Sarkozy's tactic of trying to put him on the defensive by unveiling a new campaign idea each week. "The election is not a game, it's about being coherent," he told Monday's TV show.

A separate daily survey which Ifop/Fiducial carries out using a constant sample of voters has also recorded a steady decline in Hollande's lead over the last week. Its Tuesday poll put Hollande and Sarkozy on 28 and 27 percent respectively for round one, and 55 and 45 percent for round two. ($1 = 0.7466 euros)