Texas Republican Rep. Ron Paul’s presidential campaign said Monday that he’s very unlikely to run for president as a third-party candidate.

“We don’t deal in absolutes, but there’s virtually zero chance,” said Paul campaign manager Jesse Benton. “He has no plans, no interest. It’s as close to zero as it can be without absolutely ruling it out.”

Paul’s showing at the Ames Straw Poll on Saturday — he came within 200 votes or so of winning – has forced people to take notice of his campaign.

Despite his strong showing at Ames, Paul is still given virtually no chance to win the Republican nomination as his libertarian-leaning brand of politics and distance from most Republicans on foreign policy matters make it difficult for him to win over mainstream GOPers.

But it’s become increasingly clear that Paul would cause severe problems for the GOP as a third-party candidate since he could likely win 5 or 10 percent of the vote in any given state with most of it coming at the expense of the eventual Republican nominee.

On paper, running as a third party candidate would appear to be a reasonable option if Paul’s GOP primary campaign doesn’t pan out.

Paul is not running for reelection to his House seat in 2012 and he has run as a third-party candidate before — taking less than half of 1 percent as the Libertarian Party nominee in the 1988 presidential race.

In the 2008 GOP primary, Paul took second place in 10 states and finished with the fourth-most delegates.

This year, he’s threatening to take even more, thanks to a more professional campaign operation that showed its strength in Iowa on Saturday.

Paul came within 152 votes of upsetting Rep. Michele Bachmann and actually took more votes than Mitt Romney did four years ago, when the former Massachusetts governor won the Straw Poll.

Paul’s vote total was also three and a half times as large as his showing four years ago and almost 40 percent of the total vote he got in the 2008 Iowa caucuses – where turnout is usually more than 10 times as high as the straw poll.

Paul also appears to be benefitting as the most full-throated opponent of U.S. involvement abroad from an increase in anti-war sentiment in the GOP.

In other words, the limited base of support available to Paul in 2008 has since expanded. “The mainstream has come in our direction,” Paul said during a speech at the Straw Poll on Saturday.

All of the above points to a candidate who could make some real noise in the 2012 primary and – if he felt like it – running a third party campaign.

Benton noted, though, that the practicalities of running a third-party campaign make it very difficult to seek the GOP nomination first. Some states, for example, require that a candidate filing for a primary under one party’s banner sign a pledge promising to not run with another party in the general election.

“You have to make a decision pretty early on which way you’re going to go,” Benton said, “and he’s chosen to stay in the Republican Party.”

There is also plenty of reason for Paul not to do something that would irritate the Republican Party. His son, freshman Sen. Rand Paul (R-Ky.), is a rising star in his own right and could have presidential designs of his own.

If the elder Paul were to ruin the GOP’s chances of winning the presidency next year, it could compromise the younger Paul’s standing in the party.

Altogether, it makes a third-party bid from Ron Paul intriguing but very unlikely.