With the Iowa caucus and New Hampshire primary looming a few weeks away, Republican candidates were keen to demonstrate their policy knowledge and presidential credibility during the Fox Business GOP debate Thursday. With tensions running high, here's a look at some of the best moments from the Republican showdown.

The first round of voting is set to take place Feb. 1 for the Iowa caucus and Republican frontrunners Donald Trump and Sen. Ted Cruz of Texas are polling very closely, with Trump at 27.3 and Cruz at 26.9 according to Real Clear Politics, which takes the average of available polling information. Polling data available for New Hampshire put real estate mogul Trump with a more comfortable lead, with support at 30.2 percent and Florida Sen. Marco Rubio was slated to come in second in the state at 13.2 percent, according to Real Clear Politics.

The first debate began at 6 p.m. EST and featured candidates polling toward the back of the pack, including former HP CEO Carly Fiorina, former Arkansas Gov. Mike Huckabee, and former Pennsylvania Sen. Rick Santorum. While the candidates did not make it to the main stage with the frontrunners, that didn’t stop them from trading blows with each other or from slamming Democratic leaders.

"Unlike another woman in this race, I actually love spending time with my husband," Fiorina said, in an apparent hit to Democratic frontrunner Hillary Clinton.

Former Arkansas Gov. Mike Huckabee criticized President Barack Obama's strategy in the Middle East, saying, "We have a president who seems to be more interested in protecting the reputation and image of Islam than he is in protecting us." 

Candidates on the main stage debate took turns slamming Obama and Clinton. Former New Jersey Gov. Chris Christie called Obama's State of the Union address "story time," saying the president painted a rosy-colored picture of the threats facing the nation.

Florida Sen. Marco Rubio said Clinton's track record in Benghazi "disqualified" her from being commander in chief.

Trump traded blows with Cruz over the fact that Cruz was born in Canada. Trump suggested he settle the issue in court before the Democratic party resurfaced it during the primaries. "I'm not going to be taking legal advice from Donald Trump," Cruz responded.

Trump fervently defended the second amendment, saying that a lack of mental health facilities contributed to the level of mass shootings in the U.S., and it was not a question of gun control. 

Cruz lampooned Trump for having "New York values," describing them as too liberal. Trump responded by describing the aftermath of the 9/11 terror attacks and saying Cruz had made a  "very offensive statement."