If they face each other in the May 6 second round, both candidates will have to try to win over voters who in the first round supported a range of candidates across the political spectrum, from the extreme right to the extreme left, the Times said.
Sarkozy urged members of the nationalist National Front Party this week to vote for him, saying a vote for the party's candidate, Marine Le Pen, "will only help Mr. Hollande."
Sarkozy and his supporters hope hard-left Left Front candidate Jean-Luc Melenchon, who has risen from about 6 percent to as high as 14 percent in polls, will take votes away from Hollande.
But Melenchon has indicated he would vote for Hollande in the second round, as most of his supporters would, the Times said.
Sarkozy has suggested electing Hollande would put the country at risk economically.
"Everyone in France is aware of what is happening to Spain," he said Thursday. "It is the result of seven years of Socialism with the same policies Mr. Hollande is proposing."