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.

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Vitter’s name appeared on the client list of a Washington, D.C. prostitution ring in 2007, and the senator subsequently admitted to committing a “very serious sin.” Some have suggested this incident could make him more vulnerable to a primary challenge, but at this point that appears less likely.

Vitter appears to be benefiting in part from unhappiness among Louisiana voters with the national health care plan now being pushed by President Obama and congressional Democrats. Only 34% of voters in the state favor the plan, while 64% oppose it. That's stronger opposition that is found nationally.

More importantly for Vitter, 24% strongly favor the health care plan, but 58% strongly oppose it. Against Melancon, the GOP incumbent takes 80% of the vote of that larger group that strongly opposes the plan, while the Democrats captures 81% of those who strongly favor it. Dardenne gets 76% of those who are strongly opposed, compared to Melancon's 69% of those who strongly favor.

Also working to Vitter's advantage is the finding that just eight percent (8%) in Louisiana rate the U.S. economy as good or excellent, while 50% think it's in poor condition. Only 26% say the economy is getting better, but 45% believe it's getting worse and 22% say it's staying about the same.

Sixty-one percent (61%) of Louisiana voters now have a favorable opinion of Vitter, while just 33% view him unfavorably. Among Republicans, the incumbent is viewed favorably by 86%.

Forty-nine percent (49%) of Louisiana voters view Dardenne favorably, but 24% regard him unfavorably. Sixty-eight percent (68%) of GOP voters have a favorable opinion of Dardenne.

Melancon, a congressman since 2004, is viewed favorably by 39% and unfavorably by 46%.

Just 30% in Louisiana rate the federal government’s response to the Christmas Day bombing attempt on a U.S. airliner as good or excellent, while 41% rate the response as poor. Those numbers are similar to those found on the national level.

Three-out-of-four Louisiana voters (74%) believe the bombing attempt should be investigated by military authorities as a terrorist act, rather than by civilian authorities as a criminal act.

Along with voters nationwide, most voters in Louisiana (72%) believe another terrorist attack is likely within the year, and the plurality (44%) says the United States is not safer today than it was before the September 11, 2001 terrorist attacks.

Most voters in the state (78%) also favor the use of full-body scanners at airports.

New data also has been released on Senate races in Arkansas, Colorado, Illinois, Connecticut, Missouri, Nevada, New Hampshire, North Dakota, Pennsylvania, Ohio, Texas, Florida, and California and the special election in Massachusetts.

Rasmussen Reports has released data on the 2010 governor’s races in Arizona, California, Colorado, Florida, Massachusetts, Michigan, Minnesota, New York, Ohio, Pennsylvania, South Carolina and Texas.

In 2008, Rasmussen Reports projected nationally that Obama would defeat John McCain by a 52% to 46% margin. Obama won 53% to 46%. Four years earlier, Rasmussen Reports projected the vote totals for both George W. Bush and John Kerry within half-a-percentage-point.

In Louisiana, Rasmussen Reports polled on two races during the 2008 campaign. In the race for president, Rasmussen polling showed McCain beating Obama by a 57% to 41% margin. The final election results found McCain beating Obama 59% to 40%. In the 2008 Senate race in Lousiana, Mary Landrieu defeated John Kennedy 52% to 46%. The final Rasmussen Reports poll before the election showed Landrieu winning 53% to 43%.

See all Rasmussen Reports 2008 state results for president, Senate and governor.

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