A watchdog group is launching an advertising campaign and filing an FEC complaint questioning the McCain campaign's ties to lobbyists, as Sen. John McCain and Sen. Barack Obama spar over each other's ties to special interests.

The TV ad from Campaign Money Watch, set to run on Washington, D.C., broadcast and cable outlets starting Monday, focuses on McCain's role in the awarding of an Air Force contract that would eventually go to the French company Airbus instead of the American company Boeing.

"Seven of McCain’s staff and fundraisers lobbied for Airbus," the ad says. "And guess what? John McCain intervened, which helped Airbus get that Pentagon contract. Tell John McCain to kick those lobbyists off the Straight Talk Express."

The group is also asking the Federal Election Commission to investigate two other public reports that touch on McCain's connections to lobbyists: That a lobbying company, the Loeffler Group LLP, made payments this year to McCain's national finance director, Susan Nelson; and that a company controlled in part by campaign manager Rick Davis sliced more than $100,000 off of McCain campaign's tab, when the campaign was starved for cash last year.

While working for Loeffler, Nelson lobbied on behalf of Airbus. Newsweek reported last month that Nelson was rehired early this year as a consultant for the company, while on the McCain campaign's payroll.

Campaign Money Watch alleges that the payments made by the Loeffler Group and the discount arranged by the company 3eDC could amount to illegal corporate contributions, according to an FEC complaint to be filed Monday. A copy of the group's letter to the FEC was provided to ABC News.

"That both of these matters involve excess or illegal contributions from for-profit entities raises serious questions about the McCain campaign that must be answered," the complaint states. "Simply asserting, without evidence, that they have done nothing wrong does not, in our judgment, satisfactorily answer the serious possibility that federal election law has been violated on at least two separate occasions."

The McCain campaign dismissed the allegations, calling them "baseless" and expressing confidence that the FEC complaint would be dismissed.

On the Boeing-Airbus deal, McCain aides note that the senator did not directly intervene on Airbus' behalf, but rather encouraged the Air Force to level the playing field during the bidding process.

"This is a joke," said McCain spokesman Brian Rogers. "John McCain's investigation of the bogus tanker deal saved taxpayers over $6 billion and exposed one of the biggest scandals in Pentagon history, for which executives and government officials went to jail. And now he's being attacked for fighting corruption and shaking up the status quo in Washington? It's absurd."

Campaign Money Watch is a project of the Public Campaign Action Fund, a nonprofit organization that seeks to highlight politicians' ties to special interests. Officials said they would not disclose the size of their advertising buy.