DENVER
07/14/2010 01:06 pm ET | Updated May 25, 2011

Jane Norton Ad: 'You'd Think Ken Buck Would Be Man Enough To Do It Himself' (VIDEO)

Republican Senate candidate Jane Norton's latest TV ad hist Ken Buck where it hurts, questioning her opponent's "manhood" for accepting the support of independent 527 groups.

Norton, who was once considered the clear favorite to capture the GOP nomination, has seen her lead over Weld County District Attorney Ken Buck evaporate in recent months thanks in large part to the activities of independent political groups, which have poured hundreds of thousands of dollars into ad campaigns for Buck.

"You've seen those ads attacking me," Norton says in the ad. "They're paid for by a shady interest group doing the bidding of Ken Buck. You'd think Ken would be man enough to do it himself."

Norton was specifically referencing an ad paid for by a right wing PAC called Declaration Alliance.

WATCH: