Mitt Romney backpedaled Tuesday after saying former Sen. Bob Dole is “probably the last person I would have wanted to have write a letter for me.”

Romney made the remark in response to a letter Dole wrote to conservative talk show host Rush Limbaugh in defense of Romney rival John McCain.

Romney even tried to call Dole, with no luck, from the plane as he and other candidates criss-crossed the country to campaign while voters in the 24 Super Tuesday states cast their ballots for both parties.

“Let me make it very clear. Senator Dole is an American hero, a war hero, a fine man and a great leader for our party,” Romney said in Charleston, W.Va., where GOP voters were a holding a state convention Tuesday.

The back and forth started after Dole wrote a letter to Limbaugh, who has been relentless in his criticism of McCain for being too moderate. In his letter Dole, a former GOP presidential nominee in 1996, told him to quit his attacks, and that “whoever wins the Republican nomination will need your support. Two terms for the Clintons are enough.”

Romney immediately seized on the letter, saying on FOX News Tuesday morning, “Well, it’s probably the last person I would have wanted to have write a letter for me. … I think there are a lot of folks who tend to think that maybe John McCain’s race is a bit like Bob Dole’s race — that it’s the guy who’s next in line, the inevitable choice. “

McCain shot back, saying in a statement: “Gov. Romney’s attack on Bob Dole is disgraceful, and Governor Romney should apologize. Bob Dole is a war hero who has spent his life in service to this nation and nobody has worked harder to build the Republican Party. Bob Dole deserves the respect of every American and certainly every Republican.”

In Charleston, Romney said his comment on Dole was only meant to point out that “the selection of our nominee based on someone having served in the Senate a long time … did not do well for us in that election.”

He said he was referring to “that aspect,” not Dole specifically, when he made his comments.

Romney and McCain have been tireless in accusing each other of being soft on key GOP issues, and with McCain leading in most of the Super Tuesday states Romney has been fighting to stay competitive. The former Massachusetts governor was logging more than 5,000 miles as he undertook a 37-hour coast-to-coast tour in the 21 states holding GOP contests Tuesday.

FOX News’ Carl Cameron and Shushannah Walshe and The Associated Press contributed to this report.