Former Senator Fred Thompson (R) and former New York City Mayor Rudy Giuliani are on top in polls for the Republican Presidential nomination and both men are competitive in general election match-ups with Illinois Senator Barack Obama (D).

Giuliani leads Obama 44% to 41% while Obama leads Thompson 43% to 41%. The survey’s margin of sampling error is +/- three percentage points with a 95% level of confidence.

For Giuliani, that’s a decline from last month’s 12-point lead over the man from Illinois. However, in April, Giuliani’s lead was a single point. Earlier polling had shown a very competitive Giuliani-Obama race for several months.

Obama’s two-point lead over Thompson is little changed from our previous survey. Two months ago, in May, Obama led Thompson by seven points. In March, his lead was 12 points.

While Thompson and Giuliani are frontrunners for the GOP nomination, Obama has consistently polled in second place among those seeking the Democratic nomination.

Giuliani is viewed favorably by 53% of voters, down from 63% a month ago. Forty percent (40%) have an unfavorable view.

Thompson, who has yet to formally enter the race, is viewed favorably by 46% of voters and unfavorably by 33%.

For Obama, the latest numbers are 53% favorable and 37% unfavorable.

Twenty-eight percent (28%) say they’ll definitely vote for Obama if he is on the ballot in 2008. Forty percent (40%) say they’ll definitely vote against him. For Giuliani, the numbers are 26% definitely for and 37% definitely against.

Thompson’s numbers are the lowest of the candidates on both extremes. Twenty-three percent (23%) will definitely vote for him while 31% will definitely vote against.

Rasmussen Reports continuously updates favorability ratings and general election match-ups for all Democratic and Republican candidates. Also available are continuously updated ratings for Members of Congress, Other Political Figures, and Journalists.

Rasmussen Reports releases updated polling data for the Democrats’ nominating contest are updated on Mondays. Republican results are updated every each Tuesday.