Seeking to slow Rep. David Vitter’s (R) momentum in the Louisiana open-seat Senate race, the Democratic Senatorial Campaign Committee is set to launch an independent expenditure ad buy beginning today.

The ads will run statewide and stay up through the Nov. 2 open primary, several party sources confirmed Friday.

“It is par for the course to invest early in Louisiana to start a drumbeat and start to get your message out for the runoff,” said DSCC spokeswoman Cara Morris.

The National Republican Senatorial Committee has reserved roughly $1.25 million of television time, beginning Nov. 9 and continuing until Dec. 4, the date of a scheduled runoff if none of the candidates receives 50 percent in the primary. The NRSC has not yet bought any time before Nov. 2 but has not ruled out that possibility, according to committee officials.

The decision by the DSCC to take to the airwaves is the first public acknowledgement that Vitter is a threat to win the race outright in November over the committee’s endorsed candidate, Rep. Chris John (D), and two other Democrats.

While DSCC officials would not confirm that the ads will be negatives against Vitter, a number of Democratic sources with intimate knowledge of Louisiana insisted that would be the case.

“The idea is to get a running start,” said Rich Masters, a former aide to Louisiana Sen. Mary Landrieu (D) and now a lobbyist with Qorvis Communications. “Vitter has an extreme right-wing record that no one has challenged him on.”

“You have got to put some dirt on his face,” said another D.C. Democratic operative with ties to Louisiana. “I am pretty surprised they haven’t done it before now.”

Morris called the idea that Vitter could win without a runoff a “nonstarter.”

“The consistent positive message that Chris John has been talking about combined with a strong DSCC investment will guarantee that Chris John and David Vitter go into the runoff,” she added.

The DSCC is sending down some of its top staffers — including Morris — to the Pelican State for the final weeks of the primary campaign to aid John.

Due to Louisiana’s unique election laws, Vitter, John, state Treasurer John Kennedy (D) and state Rep. Arthur Morrell (D) will all appear on the Nov. 2 ballot.

If none of the four receives 50 percent of the vote, the top two votegetters advance to a December runoff.

A slew of partisan and independent surveys have shown Vitter with a comfortable lead over all three Democrats, and, as importantly, that he is polling in the mid-40s.

There is significant concern among Democrats that given his current standing, Vitter could come dangerously close to 50 percent on Nov. 2.

Even if he misses that mark, Democrats fret that if Vitter gets above 45 percent it could provide him with significant momentum for the monthlong runoff.

As Vitter continues to rise in the polls, John and Kennedy remain in a tight race for second place.

While much of official Washington, D.C., insists that John is pulling away from Kennedy, polling continues to show the runner-up race tight.

Much of the blueprint for this Senate campaign is being drawn from the 2002 re-election race of Sen. Mary Landrieu (D-La.).

In that contest, the NRSC went up with ads that July attacking Landrieu even as the three Republicans in the race muddled far behind the incumbent.

The NRSC made the unusual decision to endorse then state Elections Supervisor Suzanne Haik Terrell (R) in August and funnelled hundreds of thousands of coordinated dollars to her campaign.

Quickly pivoting, Landrieu began running negative ads aimed at Terrell in a move designed to ensure that the Republican did not enter the runoff unscathed.

Though Landrieu was held under 50 percent in the primary, she had already begun raising questions in voters’ minds about Terrell, a strategy that paid off with a 52 percent to 48 percent runoff victory.

Masters, who was intimately involved in that contest, said the task of defining Vitter is much easier than it was with Terrell because he has a voting record from his five years in Congress.

“In 2002, we could only make allegations that Suzie would be 100 percent of the time with the Bush folks,” said Masters. “This is a guy that has a record of doing everything the hard right asks him to do.”

Even Democrats concede, however, that Vitter is a much better candidate than Terrell and has run a far superior campaign to this point.

“Democrats have good reason to be scared,” said NRSC Communications Director Dan Allen. “Vitter is running a tremendous campaign that is going to have him well-positioned for a runoff while the Democrats fight amongst themselves for second position.”