Norm Coleman continues to lead Al Franken in his defense of his U.S. Senate seat, by 48 to 45 percent, according to a poll of 500 likely voters by Rasmussen. The poll, conducted on Wednesday, June 11th, finds no bounce for Franken coming out of last weekend’s DFL convention, in which he won the party’s endorsement on the first ballot.

Coleman has now polled ahead of Fraken in 15 of 17 surveys conducted by 5 different polling organizations since February 2007. Coleman has led by single digits in each of the last five such surveys since mid-March.

Rumors of an independent candidacy by Jesse Ventura continue to linger, and the Rasmussen survey finds Ventura polling much higher in this hypothetical U.S. Senate race, than he did at this point in 1998 when he was actively running for Governor of the Gopher State. In the new Rasmussen survey, the introduction of Ventura into the mix finds Coleman with a 39 to 32 percent lead over Franken, with Ventura polling at a substantial 24 percent.

As late as August 1998, Ventura was polling at just 13 percent in his run for Governor (Pioneer Press / MPR poll), so the former Governor would be starting his Senate run with a much longer running start than he had 10 years ago. The filing deadline for Ventura to launch his candidacy is in about a month (July 15th).

Still, Ventura has the highest negatives of any of the three principles: Coleman has a 45 percent unfavorable rating, Franken has a 50 percent unfavorable rating, and Ventura has a very high 62 percent unfavorable rating. Only 27 percent believe Ventura should make a run as an independent candidate.