Who's winning early GOP debate?

As expected, Donald Trump's plan to stop additional Muslims from entering the U.S. was the main topic at the beginning

Who do you think is winning the debate?

Here are the latest developments (all times local to Las Vegas from the Associated Press):

5:05 p.m.

The Republican presidential candidates participating in the undercard debate Tuesday evening ended their faceoff on the same national security note with which they began.

South Carolina Sen. Lindsey Graham says, "Make me president, I will keep you and your family safe."

George Pataki cites his experience as New York's governor on 9/11 and says, "as a free people, we can soar to new heights."

Former Pennsylvania Sen. Rick Santorum says President Obama hasn't kept the country safe — and says Democratic front-runner Hillary Clinton would also fail at the task.

He says he has known the face of evil, and "will defeat it."

Former Arkansas Gov. Mike Huckabee says of terrorists who threaten the United States, "we have to take them out." He adds that if elected president, "I will fight for your grandkids as much as I would fight for mine."

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4:55 p.m.

Sen. Lindsey Graham once again stole the undercard show with his colorful one-liners.

Graham has been railing against rival Donald Trump for his sharp rhetoric on barring Muslims from entering the country.

He says: "Mr. Trump, you don't have to speak about everything. That's not required."

Graham also criticized Texas Sen. Ted Cruz for saying he'd be open to keeping Syrian President Bashar Assad in power. He quoted from "The Princess Bride," Cruz's favorite movie, to make his point.

He says "getting in bed with Iran and Russia to save Assad is unconceivable. Princess Buttercup would not like this."

And he says of Russian President Vladimir Putin, "I'm not afraid of a guy riding around on a horse without his shirt."

Graham also turned to humor as he tried to drive home his warning about the immediate threat the country faces from radical Islamic terrorists.

"We're at war, folks. They're not trying to steal your car," he says. "They're trying to kill us all."

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4:50 p.m.

Former Pennsylvania Sen. Rick Santorum says there is no way to safely bring Syrian refugees to the United States.

Santorum said at the GOP undercard presidential debate that it's "impossible" to check out the backgrounds of refugees coming from war-torn nations to ensure they are not planning to commit act of terrors once they arrive.

He asks: "Where are you going to go? Who are you going to call?"

Santorum also argues that moving moderate Muslims and religious minorities out of Middle East will hurt the ability of Syria and Iraq to evolve into stable states once the Islamic State is defeated.

He says if refugees come to America, they're not going to go back to the Middle East. Instead, Santorum says people fleeing from Islamic State militants should be resettled in refugee camps in the region.

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4:40 p.m.

Republican presidential candidate Lindsay Graham says there's no need to revive a military draft.

The South Carolina senator said during the presidential undercard debate in Las Vegas that he doesn't want people fighting in a war who don't want to be there.

Graham says if "you want to fix this, you get the Army to 500,000, not 420,000." The Army has said it may have to cut down to 420,000 soldiers by 2019, depending on its budget,

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4:18 p.m.

The Republican candidates for president in the undercard debate are arguing about the best strategy for using U.S. ground troops to fight the Islamic State.

Former Pennsylvania Sen. Rick Santorum says the way to beat the Islamic State is to "take their land." But he says that should involve U.S. forces training fighters in Syria.

That's earning him a rebuke from South Carolina Sen. Lindsey Graham, who says: "You're not going to win it that way, Rick. ... There is nobody left to train."

Graham wants to send 10,000 U.S. troops into Iraq and 10,000 troops into Syria to fight as part of a coalition made up mostly of troops from Arab nations in the Middle East. He says: "There must be American boots on the ground in order to win. If you don't understand that, you're not ready to be commander in chief."

Former New York Gov. George Pataki says the U.S. should send troops, but should work with partners in the region such as Saudi Arabia.

Asked how many troops he would send to the region, former Arkansas Gov. Mike Huckabee says it would be a strategic mistake to announce such a detail on stage. He says "we're going to do whatever it takes."

That, too, wins a rebuke from Graham. He defends the specificity of his plan, saying, "I don't just make this up."

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4:02 p.m.

The Republican presidential candidates debating on the undercard stage have different views of Islam and the extent to which the religion itself poses a risk.

Former Pennsylvania Sen. Rick Santorum says Islam is not just a religion, but a political governing structure and legal system. He says, "The fact of the matter is Islam is different."

South Carolina Sen. Lindsey Graham says at least 3,500 American Muslims are currently serving in the U.S. armed services and deserve to be thanked.

"Your religion is not the enemy," he says.

He says Muslim-Americans are the solution to radicals.

Graham adds: "Leave the faith alone. Go after the radicals that kill us all."

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3:50 p.m.

In the first set of questions at the GOP undercard debate, the subject is a proposal from a candidate who isn't on stage: front-runner Donald Trump and his call to temporarily bar Muslims from traveling to the U.S.

South Carolina Sen. Lindsey Graham rejects the idea out of hand, saying the plan isn't a way to keep Americans safe. Rather, he says it would encourage the Islamic State and "help our enemies."

He says the Islamic State "would be dancing in the streets, they just don't believe in dancing."

Graham asks voters to consider the how the policy would be viewed by King Abdullah II of Jordan, a Muslim. "He is our friend and he is our ally," he says.

Trump's campaign initially said his ban on Muslims entering the U.S. would apply to "everybody," but Trump later said it would not apply to leaders from Muslim nations such as King Abdullah.

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3:30 p.m.

The final Republican undercard debate of the year is now under way.

South Carolina Sen. Lindsay Graham is apologizing to allied Muslim leaders in Jordan, Egypt and elsewhere for GOP front-runner Donald Trump's proposal to ban Muslims from entering the U.S. "I am sorry. He does not represent us," Graham says.

Former New York Gov. George Pataki is striking out at Trump and Democratic front-runner Hillary Clinton. He says, "Neither is fit to be president of the United States."

Former Pennsylvania Sen. Rick Santorum declares that "we have entered World War III." He says "we have a leader who refuses to identify it and be truthful to the American people."

Former Gov. Mike Huckabee of Arkansas says people are "just plain scared" in the wake of the attacks in San Bernardino, California.

All are hoping for a breakout moment to propel them out of single digits weeks before the first votes are cast.

The top nine contenders will be taking the stage later this evening.

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3:00 p.m.

The GOP presidential candidates are using their time ahead of the debate in Las Vegas to meet with would-be donors.

Two of the top draws? Billionaire casino owners Steve Wynn and Sheldon Adelson. Wynn and Texas Sen. Ted Cruz were scheduled to talk Tuesday, and Adelson was planning to meet with Donald Trump for the first time since he became a presidential candidate. Both Wynn and Adelson are capable of writing seven-figure ?-- or more --? checks to super PACs set up to boost the candidates. Adelson is hosting the event at his Venetian casino and resort on the Strip.

A Democratic debate earlier this year was held at Wynn's Las Vegas property. When the main debate begins later Tuesday, donors will fill many of the seats in the theater because candidates often dole out their precious few tickets to those who have written big checks.

Some, including Florida Sen. Marco Rubio, also have raffled off seats at the debate as a way to entice and reward smaller donors.

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2:40 p.m.

Hillary Clinton is offering a pre-debate rebuttal to the kinds of homeland security proposals likely to be the focus at the GOP match-up.

The Democratic presidential front-runner didn't single out her rivals by name in her address at the University of Minnesota. But she left little question that she was taking aim at their proposals.

"Promising to carpet bomb until the desert glows doesn't make you sound strong, it makes you sound like you are in over your head," she said, referencing a promise Texas Sen. Ted Cruz made last week in Iowa.

She says many of the Republican candidates share the same kind of "divisive rhetoric" used by businessman Donald Trump, saying it undermines law enforcement's ability to prevent attacks at home and efforts to build global coalitions to combat the Islamic State. Trump has proposed banning Muslims from entering the country -- temporarily and with exceptions, he has said.

"Not only do these comments cut against everything we stand for as Americans, they are also dangerous," Clinton says. "We need every community invested in this fight, not alienated and sitting on the sidelines."