The survey, conducted Monday and released late in the day, indicated that Royal derived little or no momentum from the highly anticipated presentation of her presidential platform a day earlier and may even have lost ground.
The election, in two rounds on April 22 and May 6, could set the tone for the future of the European Union, whose predecessor was formed by France and five other countries more than a half-century ago.
Fifty-four percent of respondents in the poll for Paris-Match magazine released late Monday said they would support Interior Minister Sarkozy in the second-round vote, while 46 percent would back Royal.
A poll for Paris-Match in late January put Sarkozy at 52 percent and Royal at 48 percent a differential within the margin of error of plus or minus about three percentage points.
For months, the polls have been led by Sarkozy, 52, and Royal, a 53-year-old former families and environment minister who is hoping to become France's first woman president. Sarkozy first began nosing ahead slightly after his acceptance speech for the governing conservative UMP party's nomination on Jan. 14.
In the first poll, Sarkozy would garner 33.5 percent of votes in the first poll, up 2.5 percentage points from the previous Paris-Match poll. Royal dropped to 26 percent down 1.5 percentage points, according to the survey.
Among about a dozen contenders across the political spectrum expected to participate in the first round, centrist candidate Francois Bayrou got the biggest jump up 3 percentage points to 14 percent.
Bayrou overtook far-right leader Jean-Marie Le Pen, who dropped 3 percentage points to 10 percent. Le Pen stunned France five years ago by qualifying for the runoff against President Jacques Chirac, reports AP.
Chirac has not formally announced whether he will seek a third term, but he has hinted about the end of his 40-year political career recently and many pundits do not expect him to stand again.
The poll of 879 registered voters was conducted by telephone on Monday by Ifop agency. No margin of error was given, but in a poll of that size it would be plus or minus three percentage points.