Washington (CNN) -- The Chamber of Commerce is launching an ad featuring Kentucky Sen. Rand Paul, a favorite of libertarians, to build support for Alaska Republican Senate hopeful Dan Sullivan, who faces a challenge from libertarian third party candidate.

Republicans and their allies have begun work to limit how much support third party candidates draw away from GOP candidates in states which could determine control of the Senate.

In the ad Paul uses language libertarians would like to tout Sullivan, who is locked in a tight race against first term Democratic incumbent Sen. Mark Begich. Mark Fish, past chairman of the state's libertarian party, is running as well and is the wild card there because drawing even a small amount of votes away from Sullivan could prove the difference in this key race.

"Washington is horribly broken. I am Rand Paul, and I am fighting to change that. But nothing is going to change when Mark Begich votes with his liberal Democratic friends 91% of the time," Paul says in the spot. "Washington takes too many of our freedoms and too much of our money. I think Dan Sullivan will get it back. To change Washington change your Senator."

"In states like Alaska, the Chamber is focused on the independent swing vote, and we think Sen. Paul is well positioned to deliver a message that appeals to them. This fits into our them this year of using credible messengers in target races," Chamber spokeswoman Blair Latoff Holmes says in a statement.

Besides Alaska, some Republicans worry libertarian candidates could cost GOP candidates support in such key Senate battlegrounds as North Carolina, Georgia and Kentucky.

The Chamber's Alaska buy for the Paul ad is seven figures, and the spot will air statewide beginning Friday on broadcast as well as on line.

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