Republican presidential candidate Rep. Ron Paul (R-Texas), who is expected to do very well in the Iowa caucuses this week, aggressively fended off accusations on Sunday that he has engaged in 9/11 conspiracy theories and wrote a series of racist and homophobic newsletters published under his name in the 1980s and 1990s.

While Paul is no stranger to conspiracy theories, he erupted when asked by ABC's Jake Tapper about rumors that he once believed the 9/11 attacks were an inside job.

"Now, wait, wait, wait, wait," he told Tapper on "This Week." "Don't go any further on that. That's complete nonsense."

Former Paul aide Eric Dondero, who worked closely with him from 1987 to 2003, recently wrote that Paul "engaged in conspiracy theories including perhaps the attacks were coordinated with the CIA, and that the Bush administration might have known about the attacks ahead of time." Dondero said that Paul believed George W. Bush planned to use the attacks as a justification for invading Iraq, which Paul vehemently opposed, and that he expressed "no sympathies whatsoever" for the 9/11 victims.

Paul did tell Iowa voters earlier this month that "there was glee" in the Bush administration after the 9/11 attacks because it gave them a pretext to invade Iraq, and he has come under fire for his radically "non-interventionist" views on foreign policy that are out of step with the Republican mainstream. But he vehemently denies having engaged in a 9/11 conspiracy theory and would not engage in a conversation about Dondero's accusations on Sunday.

"About the conspiracy of Bush -- of Bush knowing about this? No, no, come on. Come on. Let's be reasonable," he told Tapper. "That's just off-the-wall."

Paul is soaring in the latest Iowa polls along with former Massachusetts Gov. Mitt Romney, but in the few days ahead of the vote, he has been forced to explain a number of odd and alarming moments in his political history, including a series of racist and homophobic newsletters he produced. Paul insists that he didn't write or even read the offensive comments, and he walked out of a recent interview with CNN's Gloria Berger after she repeatedly asked him about them.

On Sunday, Paul admitted to writing "a lot of part of" the newsletters, the economic parts, and acknowledged that allowing the offensive comments to be published under his name was a management error. But he insisted that his policies on the drug war, the death penalty, and the military, which disproportionately affect minorities, do more to help race relations than any of the other candidates' policies.

"On the issue of race relations, I'm the one that really addresses it," he said. "And I think that people ought to, you know, look at my position there, rather than dwelling on eight sentences that I didn't write and didn't authorize and have been, you know, apologetic about, because it shouldn't have been there and it was terrible stuff."

