Twice in the last week, Sen. John McCain has unleashed a verbal lashing against opponents of his legislative baby, an immigration reform compromise.

Both in the Senate and on the 2008 presidential campaign trail, the Arizona Republican has taken shots at those who would oppose his bill to find legal status for the 12 million illegal immigrants in the United States.

Speaking in a conference call with reporters on Monday, McCain, who has frequently said he's unapologetic about his sense of humor, took issue with criticism from former Massachusetts Gov. Mitt Romney, who last week strongly opposed the reform proposal.

McCain lobbed a two-fer against Romney, whose campaign has tried to battle image problems that he is a flip-flopper but not really a hunter.

"In the case of Governor Romney, you know, maybe I should wait a couple of weeks and see if it changes, because it's changed in less than a year from his position before. And maybe his solution will be to get out his small-varmint gun and drive those Guatemalans off his lawn. I don't know," McCain said.

Click here to hear the audio of the McCain conference call with reporters.

Feeling the sting, Romney spokesman Kevin Madden said McCain might be the one to reconsider how he wants to handle the immigration issue.

"Governor Romney has been very clear that he opposes this immigration agreement, which clearly falls short of the American public's expectations. It seems that certain candidates who brokered this flawed plan are having a very difficult time grappling with or coming to terms with the political fallout that has ensued in a substantive manner."

The slam on his 2008 primary opponent is the second such shot across the bow for McCain when it comes to his immigration credentials.

Last week, tensions ran high among Republicans negotiating the provisions of the bill. While a McCain sighting on Capitol Hill is rare these days, he was in immigration reform bill meetings last Thursday and aides stress that the White House hopeful has stayed involved from afar, often being conferenced into meetings from the road. Sen. Lindsey Graham, R-S.C., has also acted as a McCain surrogate.

But during a presentation to a gathering of Republicans who convened in the vice president's office during a break between votes on the Iraq war funding bill, Sen. John Cornyn, R-Texas, a former state Supreme Court judge, was making points near and dear to him about narrowing the scope and breadth of judicial review for immigrants who wish to protest a status decision like appealing a deportation order.

Two Republican aides with firsthand knowledge of the fracas told FOX News that McCain, growing impatient with the presentation, interrupted Cornyn and challenged his commitment to strike a deal, describing the delay with an expletive for chicken feces. McCain even suggested Cornyn just leave the room.

An incredulous Cornyn hit back at McCain by insulting his attendance record at meetings and saying the candidate can't just "parachute" into the room, the aides recounted. According to the aides, McCain then lobbed the "F" bomb at Cornyn and said he is more of an expert on immigration than anyone in the room.
A McCain spokeswoman vehemently denied that the senator had used this highly-inflammatory phrase, suggesting the senator might have used the profanity in a gerund to request that the meeting just move forward. The aide said she had never heard the senator use such a phrase in her year on his staff.
"That's a very strong accusation. I'm surprised to hear any of this even being discussed. There was certainly nothing angry, ugly, and awful like I've heard," the spokeswoman said.
Once the incident ended, there was an awkward pause, according to those in the room, and the meeting then continued. Not long after, a bipartisan deal was announced, and Cornyn put out a statement laying out his opposition to the compromise.
Speaking to FOX News on Monday, Cornyn said the whole incident had been all but forgotten.
"I don't think anything was said that people in that room hadn't heard in some other time before in their lives," Cornyn said. "It was pretty clear that he (McCain) wanted us to move forward so that they could announce their agreement."
FOX News' Trish Turner contributed to this report.