Donald Trump, Ted Cruz

Donald Trump, left, watches as Ted Cruz speaks during the CNN Republican presidential debate at the Venetian Hotel & Casino on Tuesday, Dec. 15, 2015, in Las Vegas.

(John Locher / AP)

Who do you think won the Republican presidential debate Tuesday night?

Nine candidates duked it out during a two-hour-plus prime time debate broadcast on CNN from the Venetian casino in Las Vegas, Nevada. On the main stage were businessman Donald Trump, retired neurosurgeon Ben Carson, Texas Sen. Ted Cruz, Florida Sen. Marco Rubio, former Florida Gov. Jeb Bush, businesswoman Carly Fiorina, New Jersey Gov. Chris Christie, Ohio Gov. John Kasich, and Kentucky Sen. Rand Paul.

Four candidates lagging in the polls -- Arkansas Gov. Mike Huckabee, former Pennsylvania Sen. Rick Santorum, South Carolina Sen. Lindsey Graham and former New York Gov. George Pataki -- participated in the "undercard'' debate earlier in the night.

This was the first set of GOP debates since Islamic State terrorists killed 130 people in Paris and since an American and his Pakistani wife killed 14 in a mass shooting in San Bernardino, California. ISIS dominated the discussion.

Cruz set the tone in his opening statement:

Carson, after a asking for a moment of silence for the San Bernadino victims, asked Congress for a declaration of war.

Bush and Trump clashed over Trump's idea to ban Muslims from entering the country.

Bush: "So Donald, you know, is great at -- at the one-liners, but he's a chaos candidate. And he'd be a chaos president. He would not be the commander in chief we need to keep our country safe.''

Republican presidential candidates, from left, John Kasich, Carly Fiorina, Marco Rubio, Ben Carson, Donald Trump, Ted Cruz, Jeb Bush, Chris Christie, and Rand Paul take the stage during the CNN Republican presidential debate at the Venetian Hotel & Casino on Tuesday, Dec. 15, 2015, in Las Vegas.

Trump: "Jeb doesn't really believe I'm unhinged. He said that very simply because he has failed in this campaign. It's been a total disaster. Nobody cares. And frankly, I'm the most solid person up here. I built a tremendous company and all I want to do is make America great again.''

Fiorina, the former CEO of Hewlett-Packard, said as president she would ask technology companies to help the government find and stop terrorists.

Rubio and Cruz sparred over government surveillance of Americans' phone records and immigration.

Christie, promoted from the undercard debate last time around, called President Obama "a feckless weakling'' who let the Islamic State take root in the Middle East.

Each candidate was asked to state his or her military strategy for defeating ISIS. Talk also turned to how the U.S. should respond to the Syrian refugee crisis, how to handle Russian leader Vladimir Putin and North Korean dictator Kim Jong Un.

This was the fifth and last GOP debate of 2015. There are two more debates on the Republican Party schedule before the Feb. 1 Iowa caucuses.

In the end, who do you think won Tuesday's debate? Please vote in the informal, unscientific poll above.

Related links:

» Live debate transcript from The Washington Post.

» Miss the debate? CNN has video excerpts.