Decorah, IA - Newt Gingrich likely became the first candidate to say he would not vote for Ron Paul if the  Texas Congressman were the nominee on Tuesday when he told CNN's Wolf Blitzer that "the choice of Ron Paul or Barack Obama would be a very bad choice for America."

Gingrich was critical of Ron Paul's foreign policy and the recently surfaced newsletters printed under Paul's name, which had racist remarks on them. Gingrich also said in Columbia, S.C. that Paul should explain "how he could have had a decade of newsletters that had his name on it that he apparently wasn't aware of."

The former Speaker of the House said the newsletters raised "fundamental questions" about Paul as president.

Today Gingrich said Paul - who has a large grassroots base in Iowa - as the nominee would be "difficult to see." Gingrich has been on the descent, while Paul has finally seen a boomlet in Iowa polling.

"I think it's very difficult to see how you would engage in dealing with Ron Paul as a nominee," Gingrich said.

Ron Paul previously went after Gingrich's consulting work for failed home mortgage corporation Freddie Mac, saying Gingrich Group's consultant profits of $1.6 million from Freddie Mac was actually tax payer money.

Taking a turn away from the other candidates this evening in Decorah, Iowa, Gingrich told the crowd of more than 200 that he would love to see former Secretary of State Condoleezza Rice debate Joe Biden in a vice presidential debate.

"That would be about as great a mismatch of knowledge versus ignorance as we've seen," Gingrich said. "I would be intrigued."

Gingrich said he didn't want his comments to be mistaken that he was endorsing Rice for the vice presidential nomination.

"She is a terrifically smart person, and I do think the spectacle of her debating Biden would be one of the more enjoyable moments of 2012," Gingrich said.

Gingrich joked the debate would depend on if Biden was "still on the ticket at that stage."

Gingrich continues on the second day of his Iowa bus tour Wednesday in Iowa.