Marco Rubio and Ted Cruz are locked in a tense battle that is spiraling to new heights

Presidential rivals Sen. Ted Cruz (R-Texas) and Sen. Marco Rubio (R-Florida) are locked in their second tense battle in a number of days - this time over national security and surveillance programs.

Rubio fired the opening salvo Monday at an event hosted by The Wall Street Journal.

He criticized Cruz for supporting the USA Freedom Act, which Rubio argues unnecessarily limits the National Security Agency's ability to surveil potential terrorist threats.

"At least two of my colleagues in the Senate aspiring to be president, Sen. Cruz in particular, have voted to weaken the US intelligence program," Rubio said, referencing Cruz and Sen. Rand Paul (R-Kentucky), according to The Wall Street Journal. "Weakening our intelligence-gathering capabilities leaves America vulnerable."

The USA Freedom Act eliminated the NSA's controversial bulk collection of telephone metadata, which was exposed by leaks from former contractor Edward Snowden in 2013. It requires the federal government to obtain a warrant to retrieve data from telephone companies.

Separately on Monday, Cruz made his own argument against Rubio's national-security credentials. He took a shot at Rubio's participation in the "Gang of Eight," a bipartisan Senate working group that crafted the 2013 immigration-reform bill that ultimately stalled in Congress.

Cruz said the group's proposals would have massively expanded the president's ability to admit refugees, a policy that many Republicans now oppose in light of revelations that one of the Paris attackers was reportedly found with a refugee passport.

"You know, one of my biggest concerns with the Gang of 8 bill is that it dramatically lessened the restrictions on refugee policies so it would have given President Obama the power to bring in a great many more refugees from the Middle East without properly screening them for whether they're national-security threats," Cruz told radio host Hugh Hewitt.

And though the two candidates have been relatively muzzled since in their direct attacks against each other, their campaign staffers haven't held back, engaging in open back and forth on Twitter.

Alex Conant, the Rubio campaign's communications director, attempted to tie Cruz's vote to Hillary Clinton, the Democratic presidential front-runner.

Rick Tyler, a spokesman for Cruz, fired back. He noted the majority of the members of Congress who have endorsed Rubio also voted for the USA Freedom Act.

 

The incident is only the latest rhetorical skirmish between the two campaigns.

Last week, Cruz - who has avoided using Rubio's name directly - suggested that unlike Rubio, he supported securing the US-Mexico border as a part of the 2013 comprehensive immigration-reform package that stalled in Congress. 

"Talk is cheap," Cruz said last week. "The argument that we need to secure the border first is an argument that I was making over, and over, and over again."

When asked whether Rubio supported Cruz's border-security amendments, Cruz said Rubio "opposed every single one of them."

"As a voter, when politicians are saying the exact opposite of what they have done in office, I treat that with a healthy degree of skepticism," he added.

Rubio shot back by suggesting that Cruz had actually supported a path to citizenship through his prior support for an expansion of H-1B visa program.

"Ted is a supporter of legalizing people that are in this country illegally," Rubio said, according to CNN. "In fact, when the Senate bill was proposed he proposed legalizing people that were here illegally - he proposed giving them work permits. He's also supported a massive expansion of the green cards. He's supported a massive expansion of the H-1B program - a 500% increase."

He added: "If you look at it, I don't think our positions are dramatically different."