Wednesday night on "The Colbert Report," host Stephen Colbert took umbrage at former U.S. Rep. Joe Scarborough (R-FL)'s decision to air a pro-Mark Sanford "infomercial" during Wednesday's edition of Scarborough's MSNBC show "Morning Joe."

Former Gov. Sanford (R), who left office in disgrace after admitting to an extramarital affair, is running for the U.S. House of Representatives in South Carolina's 1st District. Sanford's opponent? None other than Stephen Colbert's sister, Elizabeth Colbert Busch.

Colbert said that he hadn't planned to bring the power of his show to bear on the race, "But then I watched this morning's 'Coffee Joe and the Funky Bunch'" and saw Scarborough's wholehearted endorsement of his friend Sanford, in which Scarborough said, "It's going to be 'Morning Joe' versus 'Colbert Report.'"

"Oh," said Colbert. "It is on."

"Did I want this fight? No," he continued, then played a clip of Sylvester Stallone as Rambo saying, "But they drew first blood, not me."

Watch the clip, embedded via Comedy Central, below: