WASHINGTON (CNN) -

The U.S. Chamber of Commerce is readying an advertising blitz in the New Hampshire Senate race with a new television spot starring Mitt Romney, sources familiar with the ad buy told CNN.

The chamber is launching the ad Friday on behalf of Republican Senate nominee Scott Brown, who trails Democratic Sen. Jeanne Shaheen by anywhere from 2 to 10 points, according to recent polls.

New Hampshire is familiar turf for Romney, who convincingly won the state's first-in-the-nation presidential primary in 2012 and campaigned with Brown in Stratham earlier this summer.

The former GOP presidential nominee -- who has starred in a series of chamber-produced ads this cycle in support of business-backed Republican candidates -- is seen in the commercial seated on a sofa, tieless, talking straight to camera.

"There's one candidate who won't take orders from the White House and will buck his own party to do what's right for New Hampshire," Romney says. "That's my friend, Scott Brown."

In addition to the Romney spot, the Chamber of Commerce is set to unleash more New Hampshire ad spending in coming weeks, the sources said.

The business lobby, which is currently running the most aggressive political program in its 102-year history, is wrapping up its largest advertising buy of the election cycle this week.

On top of the New Hampshire ad spree, the Chamber of Commerce is set to air ads Friday in Arizona's 2nd Congressional District and Colorado's 6th District, two of the country's most competitive House races.

Earlier in the week, the Chamber of Commerce went live with its second TV ads in the North Carolina and Colorado Senate campaigns, also on behalf of GOP candidates.