Per Rasmussen:

Incumbent Republican David Vitter now holds an 18-point lead over his likeliest Democratic opponent, Congressman Charlie Melancon, in Louisiana’s race for the U.S. Senate, suggesting for now at least that concerns about the national Democratic agenda are outweighing those about Vitter’s 2007 link to a prostitution ring.

A new Rasmussen Reports telephone survey of likely voters in Louisiana finds Vitter leading Melancon 53% to 35%. Four percent (4%) prefer some other candidate, and eight percent (8%) are undecided.

For Vitter, the good news is that he’s now capturing over 50% of the vote. In October, he led Malencon 46% to 36%, and incumbents posting less than 50% are generally viewed as vulnerable.

Secretary of State Jay Dardenne, who has reportedly been considering a GOP Primary challenge of Vitter, also leads Melancon by 18 – 53% to 31%. Dardenne held a 13-point lead over the Democrat – 46% to 33% – in October. In that match-up, six percent (6%) currently like some other candidate, and 10% are undecided.

Vitter’s good news continued today, as Dardenne publicly pulled out of consideration for the Senate. The former state senator from Baton Rouge is a very attractive candidate for the Lieutenant Governor position now held by New Orleans mayoral candidate Mitch Landrieu; speculation has Dardenne eyeing that seat should Landrieu win and setting himself up as a leading GOP contender for governor in 2015 or even perhaps sooner should Bobby Jindal embrace national aspirations of some sort in 2012.