Former Massachusetts Governor Mitt Romney has finally surpassed New York Senator Hillary Clinton in the polls. Unfortunately for Romney, it’s a poll measuring the number of people committing to vote against him.

The Rasmussen Reports national telephone survey found that 44% of Likely Voters would definitely vote against Romney if he’s on the ballot in 2008. That’s a point higher than the 43% who would definitely vote against Clinton. Only one other possible candidate surpassed Clinton in this category all year (former House Speaker Newt Gingrich who is not considered a candidate at this time).

It’s worth noting that Clinton’s core opposition is a bit smaller than it was earlier in the year (see last month’s report). It’s also worth noting that 50% of men will definitely vote against her. Thirty-seven percent (37%) of women share that view.

The five other leading contenders for the White House have from 33% to 38% of voters committed to voting against them. Former Tennessee Senator Fred Thompson is at the low end of that list with core opposition of 33%. Former North Carolina Senator John Edwards is at 38% (see trends for all candidates).

Looking at things from the positive perspective and measuring core support, Clinton tops all candidates. Thirty-three percent (33%) would definitely vote for her. Twenty-nine percent (29%) say the same about Barack Obama while 26% are committed to voting for Rudy Giuliani.

On a net basis (core support minus core opposition) Obama comes out on top at minus 6 (29 for, 35 against). He is followed by Clinton at minus 10 (33 for, 43 against), Giuliani at minus 11 (26 for, 37 against), and Thompson at minus 13 (20 for, 33 against). These four candidates also lead the polls for their own party nomination.

In terms of partisan reaction, it’s interesting to note that 25% of Republicans say they would definitely vote against Romney while 22% of Democrats would vote against Edwards.

Among unaffiliated voters, 44% say they will definitely vote against Clinton and 41% say the same about Romney.

Clinton does a better job of uniting Republicans than any other candidate. Seventy-six percent (76%) of the GOP faithful say they’ll definitely vote against the former First Lady. Only 61% of Republicans say the same about Obama and Edwards.

Sixty-three percent (63%) of Democrats say they’ll definitely vote against Romney.