It’s the middle of August, the 29th Olympic Games in Beijing kicked off Friday and many Americans are in the midst of summer vacations. But that hasn’t cooled the air wars in several Senate races that are either competitive or have the potential to heat up down the stretch of the fall campaign.

In Kansas, Maine, Minnesota and Oregon, most of the Democratic and Republican candidates debuted their television advertising campaigns weeks ago — in some cases months ago. In Nebraska and New Mexico, the two underdog candidates finally joined the fray last week.

In Kansas, former Rep. Jim Slattery (D) went on statewide broadcast television with his fourth ad early last week. Incumbent Sen. Pat Roberts (R), who remains favored to win re-election, joined Slattery on statewide television the next day with direct rejoinder to the Democrat’s spot, which charges that the Senator has been in Washington, D.C., for too long.

Roberts has now run eight distinct television spots. The ad he put on the air Wednesday blasts Slattery for his work as a lobbyist, his profession since retiring from Congress in 1994. The ad that he launched Friday is a positive spot on veterans’ issues.

In Oregon, Sen. Gordon Smith (R) has been pounding state Speaker Jeff Merkley (D) on television for more than two months, and last week the Senator released yet another statewide ad on broadcast television critical of his Democratic opponent. In the absence of an adequately funded war chest, Merkley has been relying on the Oregon Democratic Party and the Democratic Senatorial Campaign Committee for most of his television advertising.

Smith’s latest spot attacks Merkley for his record on spending in the state Legislature. Smith’s campaign also touted an automated poll by SurveyUSA that showed the Senator with a 49 percent to 37 percent lead over Merkley, with 6 percent undecided. The Merkley campaign remains undaunted and unimpressed.

“Mr. Bipartisan is more than willing to throw Republicans and Democrats overboard to distract from his record in Washington,” Merkley campaign spokesman Matt Canter said.

In New Mexico, Rep. Tom Udall (D) had already run six television ads by the time Rep. Steve Pearce (R) hit the airwaves with his first statewide spot last week. Pearce followed that with a full-page ad in the Albuquerque Journal newspaper, before launching his first radio ad of the general election campaign.

That radio spot charges Udall with siding with “radical environmentalists” and blocking sensible energy policies to lower energy costs.

In Nebraska, long-shot Democratic candidate Scott Kleeb ran his first television ad on statewide broadcast television Friday night during the opening ceremonies of the Olympics. The buy was small, although the the Kleeb campaign claimed that it was going up with a larger buy this week in multiple markets over “several days.”

Kleeb’s ad is a positive spot that focuses on bringing “change” to Washington. Kleeb’s opponent, former governor and ex-Agriculture Secretary Mike Johanns, has not run a television spot since cruising to victory in the May 13 GOP primary. Johanns remains an overwhelming favorite in this race, with his campaign basically yawning upon being informed of Kleeb’s television spot.

“Mike Johanns will continue talking to Nebraskans about his plans to work across the aisle for real solutions for a comprehensive energy policy to lower energy costs and to create good jobs,” Johanns campaign spokeswoman Sarah Pompei said.

Also this week Rep. Tom Allen (D-Maine) began running his first ad in his campaign against Sen. Susan Collins (R).

The 60-second ad, titled “Real Choice, Real Change,” focuses largely on hammering home a message of change. Allen introduces himself by telling viewers that he voted against the war in Iraq and that he supports setting a responsible deadline to bring troops home.

“The billions spent there are needed to solve problems here,” he says in the spot.

Polls have consistently showed Allen trailing Collins, a moderate Republican in a Democratic-leaning state.