Washington (CNN) New Jersey Gov. Chris Christie once again has his sights trained on Kentucky Sen. Rand Paul.

Christie reprised his favorite line of attack against Paul in national TV interviews and on the trail Sunday and Monday morning, slamming the libertarian-leaning senator for his opposition to the NSA's domestic surveillance programs.

"We're going to look back on this and he should be in hearings in front of Congress if the country is attacked," Christie said of his fellow Republican presidential contender in an interview on MSNBC's "Morning Joe."

On Sunday, Christie charged that Paul's actions had made the country "weaker and more vulnerable."

Paul led the charge against the domestic surveillance programs authorized under the Patriot Act this spring, leading to the programs' temporary expiration and the ultimate triumph of reform efforts that Paul insisted did not go far enough. Paul also used his marathon 10-hour speech on the Senate floor to raise money, with his campaign sending out an email to supporters to fundraise off the effort.

"It's disgraceful," Christie said of the fundraising Monday.

Christie, though, also benefited financially off the NSA debate as his political action committee, Leadership Matters for America, also sent out fundraising emails asking supporters to chip in to help Christie stand up to the anti-surveillance efforts of Paul and others.

Christie was Paul's chief antagonist among the more than a dozen White House hopefuls during Paul's headline-grabbing anti-surveillance moves in the Senate this spring. The blunt governor accused Paul of endangering the lives of Americans and overblowing the extent of government surveillance on Americans.

Paul shot back at Christie saying the governor worried about the "dangers of freedom" versus "the danger of losing that freedom." And of Christie's remark labeling Paul as one of the "misguided ideologues who have no real world experience in fighting terrorism," Paul retorted that that comment "just wasn't very nice."

Under the Patriot Act, the NSA gathered the call records of millions of Americans without a targeted warrant, a practice Paul and other civil libertarians -- including other Republicans -- argued violated Americans' rights. The new system will force the NSA to get a warrant to obtain call logs for specific individuals.

Christie is lobbing the same line of attacks at Paul, but this time the ante has been upped, since Christie and Paul are now officially opponents in the GOP presidential race. Christie announced his bid last week.

Photos: Chris Christie's career in photos New Jersey Gov. Chris Christie, joined by his family, announces his candidacy for the Republican presidential nomination on June 30 at Livingston High School in Livingston Township, New Jersey. Hide Caption 1 of 21 Photos: Chris Christie's career in photos Christie takes questions from Bruce Rastetter at the Iowa Ag Summit on March 7 in Des Moines, Iowa. Hide Caption 2 of 21 Photos: Chris Christie's career in photos Christie jokes with host Laura Ingraham as he addresses the annual Conservative Political Action Conference at National Harbor, Maryland, on February 26. Hide Caption 3 of 21 Photos: Chris Christie's career in photos Christie campaigns for Wisconsin Gov. Scott Walker during a campaign stop at the GOP field office in Hudson, Wisconsin, on September 29, 2014. Hide Caption 4 of 21 Photos: Chris Christie's career in photos Christie enters the Borough Hall in Fort Lee, New Jersey, on January 9, 2014, to apologize to Mayor Mark Sokolich for the George Washington Bridge lane closures -- a scandal that became known in the media as "Bridgegate." Hide Caption 5 of 21 Photos: Chris Christie's career in photos Christie speaks at a news conference on January 9, 2014, in Trenton, New Jersey, about his knowledge of an alleged traffic study that stopped traffic at the George Washington Bridge. Christie addressed allegations that his deputy chief of staff signaled for the New York and New Jersey Port Authority to close lanes on the George Washington Bridge to punish the Fort Lee mayor for not endorsing Christie during the election. Hide Caption 6 of 21 Photos: Chris Christie's career in photos Christie arrives to speak at his election night event after winning a second term as governor on November 5, 2013, in Asbury Park, New Jersey. Christie defeated his Democratic opponent, Barbara Buono, by a large margin. Hide Caption 7 of 21 Photos: Chris Christie's career in photos Christie talks to business owners affected by a massive fire that burned a large portion of the Seaside Park boardwalk, which had recently been rebuilt after Superstorm Sandy, on September 14, 2013, in Seaside Heights, New Jersey. Hide Caption 8 of 21 Photos: Chris Christie's career in photos Christie speaks to members of the Hudson County Building Trades Council after receiving their support for his re-election campaign for governor on July 1, 2013, in Jersey City, New Jersey. Hide Caption 9 of 21 Photos: Chris Christie's career in photos Christie greets President Barack Obama on his arrival in Atlantic City, New Jersey, on October 31, 2012, to visit areas hit by Superstorm Sandy. Christie was later criticized by some in his party for his warm welcome of Obama. Hide Caption 10 of 21 Photos: Chris Christie's career in photos Christie updates members of the media on damage and recovery efforts related to Superstorm Sandy on October 30, 2012, from the emergency operations center at State Police Headquarters in Ewing, New Jersey. Hide Caption 11 of 21 Photos: Chris Christie's career in photos Christie and Republican presidential candidate Mitt Romney speak with Romney adviser Bob White on board the Romney campaign bus in Mount Vernon, Ohio, on October 10, 2012. Hide Caption 12 of 21 Photos: Chris Christie's career in photos Christie takes the stage to deliver the keynote address at the Republican National Convention on August 28, 2012, in Tampa, Florida. Hide Caption 13 of 21 Photos: Chris Christie's career in photos Christie speaks as he endorses former Massachusetts Gov. Mitt Romney for the Republican presidential nomination on October 11, 2011, in Lebanon, New Hampshire. Hide Caption 14 of 21 Photos: Chris Christie's career in photos Christie and his family lay white roses on wreckage pulled from Ground Zero during the dedication of the Empty Sky Memorial for 9/11 at Liberty State Park in Jersey City, New Jersey, on September 10, 2011. Hide Caption 15 of 21 Photos: Chris Christie's career in photos Christie speaks at a Reform Agenda Town Hall meeting at the New Jersey Manufacturers Insurance Company facility on March 29, 2011, in Hammonton, New Jersey. Hide Caption 16 of 21 Photos: Chris Christie's career in photos Christie, his wife, Mary Pat Christie, and their children attend the third annual New Jersey Hall of Fame Induction Ceremony in Newark, New Jersey, on May 2, 2010. Hide Caption 17 of 21 Photos: Chris Christie's career in photos Christie waves to supporters with Lt. Gov.-elect Kim Guadagno, left, on November 3, 2009, in Parsippany, New Jersey. Christie defeated incumbent Democrat Jon Corzine. Hide Caption 18 of 21 Photos: Chris Christie's career in photos Christie and his running mate, Kim Guadagno, left, pose for photographs after making phone calls to voters at Monmouth County Republican Headquarters in Freehold, New Jersey, on November 2, 2009. Hide Caption 19 of 21 Photos: Chris Christie's career in photos Before getting into politics, Christie was a New Jersey attorney. Here Christie speaks with the media on May 8, 2007, outside the federal courthouse in Camden, New Jersey, after six men were arrested on charges of planning to attack the Fort Dix military base. Hide Caption 20 of 21 Photos: Chris Christie's career in photos Christie speaks to the media about an FBI sting with Russian Gen. Sergei Fomenko, right, of the Federal Security Service and FBI Agent Louie Allen on August 13, 2003, in Newark, New Jersey. Hide Caption 21 of 21

The two haven't just grappled over national security issues. Paul has knocked Christie over appearing in an ad touting New Jersey's recovery post-Hurricane Sandy (calling it a "black eye" on recovery efforts) and Christie's blunt approach to handling a heckler last year, or as Paul called it, Christie's "bully demeanor."

And the two Republicans are also vying for the same prize: the New Hampshire primary. Both Christie and Paul camps are chasing votes in the Live Free or Die state, which is home to the second GOP nominating contest.

And while Paul currently sits in fourth place with 9% in a CNN/ORC poll released last week, Christie is behind in sixth place with 5%.

But Christie is looking for a political comeback after the Bridgegate scandal undercut his steady political rise, and New Hampshire is where his aides say Christie will resonate the most among the early states.