The Republican presidential candidates turned their fire on Rep. Ron Paul at Thursday�s debate, showcasing what�s become the Texas Republican�s Achilles� heel in the Republican primary: his foreign policy views.

Paul�s positions on national security remain his biggest obstacle to a realistic chance at the GOP nomination, even as he�s shot up in the polls in Iowa on his steadfast libertarian economic views.

Paul called the war in Iraq �useless� Thursday and said Iran shouldn�t be bombed to stop it from getting nuclear weapons � positions loathed by many Republicans.

Pundits give Paul a legitimate shot at winning the wide-open Iowa caucuses on his economic message, but say he�s unlikely to go much further.

In Paul�s 1988 and 2008 presidential campaigns, he was mostly viewed as a fringe candidate trying to publicize his views. But the libertarian�s economic message has been tailored to this year�s anti-government sentiment among GOP voters, and he�s slowly risen in the Iowa polls behind a fervent base.

The disparity between Paul and the rest of the Republican field was on full display at Thursday�s Fox News debate, where the candidates who trail Paul escalated their attacks on him.

Rep. Michele Bachmann (R-Minn.) called his positions on Iran �dangerous� as she and Paul had a terse exchange over whether the country is getting close to obtaining nuclear weapons.

Paul said there wasn�t evidence the country was producing weapons, and that �the greatest danger is that we will have a president that will overreact, that we will soon bomb Iran.�

Bachmann responded that she�d �never heard a more dangerous answer for American security than the one that we just heard from Ron Paul.�

�The problem would be the greatest under-reaction in world history if we have an avowed madman who uses that nuclear weapon to wipe nations off the face of the Earth,� Bachmann said.

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