As Rojas states at The Crossed Pond, it will come when one or more of them start to co-opt his rhetoric:

This is how insurgencies change the political landscape. Not by winning, necessarily, but by demonstrating that there’s money and votes to be had by shifting ground towards the insurgent’s position. Some will say that Ron Paul supporters are too far gone from the rest of the Republican Party to be drawn back in. But the people who say that have been wrong–demonstrably, factually wrong, at every stage–in their predictions about Paul’s campaign. The minds that matter are no longer listening to them. Paul’s supporters can be Republican voters and Republican donors in November. These people are a keystone element of any winning Republican coalition. It is only a matter of time before some strategist for a top tier campaign realizes this. Who will move first? Will McCain suddenly rediscover his hardcore opposition to torture and support for habeas corpus rights? Will Fred Thompson reinvent himself as a supporter of genuinely limited government and as an outright opponent of Bush-style “compassionate conservatism”? Will Giuliani endorse the gold standard? Will Huckabee start bashing the North American Union? Will–dare we imagine it–a second Republican candidate come out against the war in Iraq? Keep your ears open. The moment is coming. Not if, but when.

Of all the candidates mentioned, I doubt it will be Giuliani. He is the front-runner and likely destined to remain so at least until the first votes are actually counted. McCain is too wedded to the neo-cons to be taken seriously as anything else. And Huckabee, well, he wasn’t able parlay a surprisingly good showing in the Ames Straw Poll into anything more than an additional $ 300,000 in the second quarter.

Of all the candidates mentioned, the most likely one to adopt a limited government platform like Ron Paul’s is Fred Thompson. He already has supporters comparing him to Ronald Reagan despite the fact that, while he was in the Senate, he voted more like George H.W. Bush. And the libertarian/limited government strain of Reagan’s Presidency is one that still has support among the conservative wing of the party, especially those who have grown disillusioned with the Bush Administration of late.

Some, if not most, Ron Paul supporters will probably cry foul when this happens, whether it’s Thompson or someone else, but they shouldn’t.

When your opponents start talking the same language you are, it means that the recognize that you have something worth listening to.