WASHINGTON — Republican presidential hopefuls spoke up strongly for the anti-terror Patriot Act in a campaign debate Tuesday night, saying it should be extended or perhaps strengthened to help identify and capture those who would attack the United States.

Only Rep. Ron Paul of Texas among eight presidential hopefuls dissented, arguing that the law is “unpatriotic because it undermines our liberties.”

In a debate on national security, Minnesota Rep. Michele Bachmann said President Obama has “essentially handed over our investigation of terrorists to the” American Civil Liberties Union. “Our CIA has no ability to investigate,” she said. Bachmann did not cite any examples to buttress either of her claims.

The debate unfolded six weeks to the day before the Iowa caucuses inaugurate the competition for delegates to the Republican National Convention. The venerable DAR Constitution Hall was the site.

The Patriot Act is one of the nation’s principal tools in ferreting out terrorist threats but has often provoked dissents from both liberals and conservatives who argue that in the name of national security it erodes constitutional protections.

Paul made that point, and said other investigative techniques captured Oklahoma City bomber Timothy McVeigh.

Gingrich jumped at that. “That’s the whole point. Timothy McVeigh killed a lot of Americans,” the former House speaker said. “I don’t want a law that says after we lose a major American city, we’re sure going to come and find you. I want a law that says, you try to take out an American city, we’re going to stop you.”

Neither Gingrich nor any other Republican mentioned that Obama, like President George W. Bush before him, signed legislation extending the Patriot Act.

In a race that is constantly in flux, Gingrich has emerged as Romney’s principal rival atop the public opinion polls.

The debate ranged widely over foreign policy issues.

Asked if he would support an Israel attack on Iran to prevent the Islamic regime from acquiring a nuclear weapon, Cain said he would want to know what the plan was and have an understanding of its chance of success.

Gingrich said he would bomb Iran only as a last resort and with a goal of bringing about the downfall of the government.