This story was updated April 23, 2018, at 11:44 p.m.

NASHVILLE — Vice President Mike Pence on Monday doubled down on his support of Republican U.S. Senate hopeful Marsha Blackburn, calling her a "critical ally" in a tweet that comes a day after retiring U.S. Sen. Bob Corker, R-Tenn., offered more muted support for the Brentwood congressman.

"PROUD to support our friend @VoteMarsha for US Senate representing Tennessee," the vice president tweeted. "Marsha Blackburn is a rock-ribbed conservative who has been a champion of President Trump's pro-jobs, pro-military, AMERICA FIRST agenda & will be critical ally in the Senate. She has our full support!"

Pence had made his support of Blackburn clear last year when his Great America PAC gave $10,000 to the Senate hopeful, who at that point faced former U.S. Rep. Stephen Fincher in the GOP primary.

Fincher later dropped out of the race and Corker briefly weighed reversing his decision to step down as he completes two Senate terms.

Corker has come under criticism for his praise of longtime friend and former Tennessee Democratic Gov. Phil Bredesen, Democrats' expected Senate nominee.

Corker has said he won't campaign against Bredesen, a former Nashville mayor.

As a state finance commissioner, former Chattanooga mayor and later as senator, Corker had worked with Bredesen on projects ranging from luring the now-Tennessee Titans NFL franchise to Nashville to encouraging Volkswagen to locate its U.S. auto assembly plant in Chattanooga.

Making the rounds of network news shows on Sunday, Corker made no apologies about his friendship with Bredesen.

"He is my friend," Corker told CNN's Dana Bash. "I'm not going to campaign against him, but I'm supporting our nominee."

Asked why Blackburn would be better than Bredesen, Corker said, "I think most people in our state, it is a red state, will focus on the first vote she makes, and that's the vote to elect the majority leader. And at the end of the day, I think that's going to be a big factor in the race."

As Bash said that didn't exactly sound like a "ringing endorsement" of Blackburn, Corker replied, "I'm supporting the nominee. I've worked with the nominee for some time, and I don't know what else to say."

He never mentioned Blackburn by name.

Last week, President Donald Trump tweeted out his support of Blackburn, vowing to come to Tennessee and campaign on her behalf.

Contact Andy Sher at or 615-255-0550.