Gop candidates clashes over terrorisms and national security

A more lively Jeb Bush jabbed Donald Trump and the increasingly public rivalry between Marco Rubio and Ted Cruz spilled into the open Tuesday night during the final Republican presidential debate of the year.

Bush, the former Florida governor whose campaign is floundering, appeared eager to hit the GOP front-runner at the CNN debate and asserted himself more effectively than in previous debates. The two men exchanged tense words on Trump's plan to temporarily ban Muslims from entering the United States as well as his recent vow to go after family members of ISIS terrorists.

The latter, Bush said, was "another example of (Trump's) lack of seriousness."

Trump, visibly annoyed, at one point could be seen mouthing, "Give me a break." He delivered his usual attack line on the ex-governor: that he is simply too nice.

"I think Jeb is a very nice person, very nice person," Trump said. "But we need toughness."

As Bush interjected, Trump taunted: "You're trying to build up your energy but it's not working."

Bush shot back: "Donald, you're not going to be able to insult your way to the presidency."

Rubio and Cruz, meanwhile, tussled over a string of issues, including the National Security Agency's surveillance program, immigration reform and how the United States should respond to dictators in the Middle East. Rubio blasted Cruz for voting for the USA Freedom Act -- a law that makes it more difficult for the government to access people's phone records.Here's the world we live in. This is a radical jihadist group that is increasingly sophisticated," said Rubio, who voted against the act. "We are at a time when we need more tools, not less tools."

Cruz called Rubio's accusation simply false, and said the law ultimately "strengthened the tools of national security and law enforcement to go after" terrorists.

The GOP debate comes in the aftermath of deadly terror attacks that shook Paris and San Bernardino, California. Those events upended the narrative and focus of the 2016 presidential campaign, making national security a top-tier issue.

CRUZ AND RUBIO

The long-running feud between the Cruz and Rubio has intensified as both men have risen in the polls and are seeking to seize the second place spot after Trump. Cruz is attempting to straddle the line between being an outsider candidate and one who can appeal to the establishment. Rubio has tried to blunt Cruz's rise by attacking his national security policy as too isolationist -- a potent attack at a time when national security is dominating the campaign.

Cruz hit Rubio on one of the Florida senator's biggest political vulnerabilities: Rubio's work on the "Gang of Eight" comprehensive immigration reform bill. Calling the legislation a "massive amnesty plan," Cruz accused Rubio of working with Democrats to give Obama a "blanket authority" to accept refugees."He was fighting to grant amnesty and not to secure the border. I was fighting to secure the border," Cruz said.Rubio hit back, saying Cruz supports the legalization of people who are in the country illegally. He also slammed his colleague for supporting a controversial H-1B visa program, which supports immigration of highly skilled foreign workers.

Cruz and Rubio also split on whether the turmoil in the Middle East would ease if Syrian President Bashar al-Assad was removed from power."If we topple Assad, the result will be ISIS will take over Syria and it will worsen U.S. national security interests," Cruz said.

Rubio rejected this notion, saying while the United States must sometimes work with "less than ideal governments," Assad was simply an "anti-American dictator.