Retiring Tennessee Senator Bob Corker (R) has recently said glowing things about a candidate angling to fill his seat in the Senate this year. Unfortunately for the GOP, those nice things were all about the Democrat in the race, former governor Phil Bredesen. “He was a very good mayor, very good governor, very good businessperson,” Corker said of his longtime friend Bredesen.

A recent poll shows Bredesen with a 10-point lead over his likely GOP opponent, Rep. Marsha Blackburn, a tea party favorite, climate denier and original sponsor of the first congressional “birther bill” aimed at forcing President Obama to release his birth certificate to prove he was an American citizen.

Corker’s laudatory comments about Bredesen prompted a tongue-lashing from Senate Majority Leader Mitch McConnell (R-Ky.) and a reminder that Corker’s unexpected retirement is the reason the GOP majority in the Senate hangs in the balance. Corker got back in line and later tweeted that he was donating money to Blackburn’s campaign and would vote for her.

But this morning on CNN, host Dana Bash attempted to get Corker to explain why anyone ought to vote for Blackburn. Despite his Twitter endorsement, Corker had a little trouble. The best he could do was suggest that a vote for Blackburn could be critical to the GOP retaining control of the Senate and of course, re-electing McConnell as Senate Majority Leader.

Watch the exchange below: