Sanford ties Colbert Busch to 'big labor' in new ad

"That's Elizabeth Colbert Busch fighting for big labor," the ad's narrator says. "Colbert Busch is funded by labor union special interest money, even the one trying to shut down Boeing. In Congress she'll return the favor."

Sanford and Colbert Busch, a businesswoman and sister of comedian Stephen Colbert, will face each other in a May 7 special election to fill the House seat vacated when former Rep. Tim Scott (R) was appointed to the Senate. 

Sanford is facing an increasingly difficult race despite the district's conservative lean and is hoping that tying Colbert Busch to unions — which are highly unpopular in the district — can help stabilize his campaign.

Colbert Busch has been endorsed by the South Carolina chapter of the AFL-CIO. Sanford has previously called on Colbert Busch to return a $5,000 donation from the International Association of Machinists, which once sought to prevent Boeing from building a new manufacturing facility in South Carolina.  

Sanford endured a potentially fatal blow to his House campaign last week when court documents surfaced showing his ex-wife, Jenny, has accused him repeatedly trespassing at her home. 

The allegations prompted the National Republican Congressional Committee to announce it wouldn't help him in the race. 

Sanford responded with a full-page ad in a local paper over the weekend comparing his struggle to the Alamo (though he misstated the year of the battle — it was 1836, not 1863, as he'd written).

Sanford trailed Colbert Busch by 9 points in a poll released Monday afternoon from the Democratic-affiliated Public Policy Polling. Mitt Romney carried the district by 18 points in 2012.

Sanford's new ad is meant to counter a barrage of on-air attacks he has faced in the past week by Democrats and outside groups supporting Colbert Busch. 

The Democratic Congressional Campaign Committee is spending about $205,000 on ads — which are running through April 28 on broadcast stations in the Charleston and Savannah markets in Georgia — hitting Sanford over his alleged ethics violations as governor.

Also last week, House Majority PAC launched its own three-week, six-figure media campaign against Sanford over his alleged misuse of taxpayer funds for flights to France, China and Argentina.

And a veterans' group, VoteVets Action Fund, began advertising this week against Sanford, targeting him over his 2009 extramarital affair with an Argentinian woman and his claims at the time he'd been hiking the Appalachian Trail.