A new national opinion poll in the U.S. presidential race indicates Republican Senator John McCain and Democratic Senator Hillary Clinton are each in the lead for their party's nomination.

Clinton, who has consistently led in national polls, was first among Democratic contenders with 42 percent support.  Senator Barack Obama, who registered 21 percent in a similar poll in December, now has 33 percent support.

In South Carolina, where the next election contest takes place Saturday, Obama leads Clinton 39 percent to 24 percent.  Former Senator John Edwards, who is solidly in third place in national polls, has 19 percent support in the state.

Republican candidates hold a televised debate Thursday in Florida, where polls indicate Senator McCain and former Governor Mitt Romney are locked in a tight contest for first place.  Polls show former Governor Mike Huckabee, who has reported he is low on campaign funds, and former New York Mayor Rudy Giuliani, who has staked much of his campaign on winning the Florida primary, are vying for third place.

In the Democratic contest, news coverage in recent days has focused on the role race and gender are playing in the rivalry between Barack Obama and Hillary Clinton.

Barack Obama's lead in South Carolina has been attributed to strong support from black voters.  National polls indicate Hillary Clinton is favored by female voters.

Some information for this report was provided by AFP, AP and Reuters.