Democrats are questioning a new ad campaign launched in support of state Sen. Scott Brown’s (R) Senate campaign in Massachusetts, but a spokesman for the group behind the ad, Americans for Responsible Health Care, says it activities are perfectly legal.

Questions about the group, which began running $200,000 worth of ads in Boston on Wednesday, center on the involvement of New Hampshire Senate candidate William Binnie, a Republican investment banker, who appears in one of the ads.

Democratic Senatorial Campaign Committee spokeswoman Deirdre Murphy said in a statement that Binnie is breaking the law because “Senate candidates are, by law, not allowed to form a ‘527’ Issues Advocacy Group and run television advertisements for other candidates.” And she asked whether Brown would denounce the ads and their message.

Jeff Cohen, the group’s spokesman, acknowledged that Binnie was “a catalyst” for its formation, but said he “did not form or fund Americans for Responsible Health Care.”