NASHUA, NH - APRIL 18: U.S. Sen. Rand Paul (R-KY) speaks at the First in the Nation Republican Leadership Summit April 18, 2015 in Nashua, New Hampshire. The Summit brought together local and national Republicans and was attended by all the Republicans candidates as well as those eyeing a run for the nomination. (Photo by Darren McCollester/Getty Images) *** Local Caption *** Rand Paul Sen. Rand Paul (R-KY) speaks at the First in the Nation Republican Leadership Summit on April 18, 2015 in Nashua, N.H. (credit: Darren McCollester/Getty Images)

WASHINGTON (CBSDC/AP) — Republican Sen. Rand Paul lashed out against the federal government’s sweeping surveillance programs on Wednesday, staking an aggressive position on an issue already dividing the Republican presidential field.

The libertarian-leaning Kentucky Republican, who launched a White House bid earlier in the month, noted that members of his own party support programs that allow the National Security Agency to collect the phone records of millions of Americans.

“Our Founding Fathers would be mortified,” Paul said during an awards ceremony hosted by the Constitution Project, a Washington think tank.

The federal government’s surveillance programs could play prominently in the GOP presidential primary contest, which is heating up just as Congress debates surveillance programs initiated by President George W.Bush’s administration and continued under President Barack Obama.

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In a Tuesday radio interview, former Florida Gov. Jeb Bush, who is expected to run for the GOP nomination, praised the Obama administration’s use of “big metadata programs” that began under Bush’s older brother.

“There has been a continuation of a very important service,” Bush said. “The first obligation, I think, of our national government is to keep us safe. And the technologies that now can be applied to make that so, while protecting civil liberties, are there.”

Congress is now deciding whether to renew or modify the phone records collection when the law authorizing it expires in June. Senate Republicans this week introduced a bill to allow the NSA to continue collecting the calling records of nearly every American, unveiling a measure that would bypass Senate committees and reauthorize sections of the USA Patriot Act.

Intelligence officials say the program — it collects the “to” and “from” information of most domestic landline phone calls but not their content — is critical to detecting terrorist plots and have sought to justify it through the ongoing declassification of materials, including from the Foreign Intelligence Surveillance Court.

Paul has promised to enact an executive order to end such government surveillance programs on his first day in office should he win the presidency.

On Wednesday, the first-term Kentucky senator took an apparent jab at Arizona Sen. John McCain’s defense of the surveillance.

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“One unapologetic senator who I’ve had a few rounds with said, ‘If you’re not talking to terrorists, why are you worried?'” Paul said. “Have we fallen so low that that is our standard? If you have nothing to hide you have nothing to fear? It’s a long way from innocent until proven guilty.”

In an interview with Fox News, McCain called Paul “the worst possible candidate” on national security.

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