(CNN) - Robert Portman, the director of the Office of Management and Budget, formally endorsed John McCain's White House bid Tuesday, hailing the Arizona senator as a "proven leader with a track record of breaking through partisan gridlock in Washington."
"He has been an effective champion for fiscal responsibility and pro-growth economic policies. No one is a more committed advocate for our men and women in uniform, and no one understands better the threats America faces," Portman, a former congressman from Ohio, said in a statement released by the campaign.
Portman is often mentioned as a potential pick for vice president given his fiscally conservative credentials and ties to Ohio - a crucial swing state in the general election.
McCain's campaign also announced the backing Tuesday of six former chairmen of the Republican National Committee.
Related: Potential V.P. picks stay mum
– CNN Ticker Producer Alexander Mooney
Mr. Portman is correct about John McCain's proven record of "crossing the aisle" to work with Democrats on legislation beneficial for our country. There is no evidence that Senator Obama has ever worked with Republicans in a similar way.
This is a good endorsement.
Oh Good Grief.... another chant from an Obama follower... Yes, we are America... I'm a little nauseous.
I prefer "Yes We Con"
The repugs have each-other's backs. I'm just shocked!
Govenor Ed Rendell of PA supports Hillary!
bring it home Hillary! PA is ready to vote.