Romney featured in Montana Senate ad

Mitt Romney is appearing in another U.S. Senate ad, this time backing Rep. Denny Rehberg of Montana in his challenge to incumbent Democrat Jon Tester.

Rehberg and Tester are deadlocked in Montana, according to recent statewide polls compiled by RealClearPolitics. The race is one of a handful that will decide whether Democrats continue to control the U.S. Senate.

"The stakes are high, Montana," Romney says in the ad, according to a Lee Newspapers story. "I urge you to send Denny to the Senate, and we'll get America back on track."

Romney has been concentrating primarily on his own race for the White House and has only dipped into a couple of Senate races. He starred in an ad for Indiana's Richard Mourdock earlier this month. Romney also cut an ad for Utah's Orrin Hatch during the veteran senator's GOP primary earlier this year.

The Montana newspaper story said the Romney-Rehberg ad began airing Monday. The ad war in Montana is tops in the nation, with more than 25,211 campaign commercials running in the Senate race so far this month.