7 Moments That Mattered at the 5th Republican Undercard Presidential Debate

— -- Four presidential candidates whose combined national polling numbers are in the low single digits, gathered on a debate stage in Las Vegas on Tuesday night with seemingly little hope of breaking into the top tier as the first nominating contests of 2016 approach.

Fielding questions from CNN moderator Wolf Blitzer, each of the Republican contenders sought to convince voters, for the last time this year, that they deserve another look.

Former Arkansas Gov. Mike Huckabee, who was lucky enough to make the main stage debate for the first three GOP debates, was given the boot again to what has been called the “kids table” debate, joining three other low-polling regulars: South Carolina Sen. Lindsey Graham, former Pennsylvania Sen. Rick Santorum, and former New York Gov. George Pataki.

Here’s a look at 7 moments that mattered at the final “undercard” debate of 2015:

Candidates pile on Donald Trump

Graham sharply rebuked the Republican frontrunner early in the debate for his controversial proposal to ban Muslims from entering the United States.

“Donald Trump has done the one single thing you cannot do: Declare war on Islam itself. ISIL would be dancing in the streets, they just don't believe in dancing,” Graham said. “This is a coup for them and to all of our Muslim friends throughout the world.”

Pataki joined in Graham’s criticism: “To target a religion and say that regardless of whether you're an American soldier who has fought on our side our allies we have overseas simply because of your religion we'll ban you is un-American. It is unconstitutional and it is wrong.”

Santorum called Trump’s idea “not the right proposal” and Huckabee referred to the proposed ban as “impractical.”

And a few defend him too

For all the candidates’ criticism of Trump, his GOP rivals Huckabee and Santorum said he started an important conversation.

“He brings up a very important issue that I think we've been ignoring for far too long,” Santorum said. “The reality is that, yes, we need to get reformist Muslims to join us.”

Huckabee agreed, arguing Trump’s plan is impractical but acknowledged he “has touched a nerve because people are angry and afraid that we are facing an enemy that this administration refuses to acknowledge, refuses to want to go fight.”

Rick Santorum: ‘Islam is different’

Responding to a question asked earlier of several other candidates -- whether surveillance of American Muslims violate their First Amendment rights -- Santorum offered a forceful take.

“The fact of the matter is, Islam is different,” Santorum said. “I know this is going to come as a shock to a lot of people. I mean that sincerely. Islam is not just a religion. It is a political governing structure.”

Graham on Muslim-Americans: ‘You are not the enemy’

Shortly after Santorum’s comments, Graham underscored the importance of not targeting the Muslim community.

“There are at least 3,500 American-Muslims serving in the armed forces. Thank you for your service. You are not the enemy. Your religion is not the enemy,” Graham fired back. To demonstrate his point, the South Carolina senator shared a personal experience he had while in Afghanistan for its second presidential election with a Muslim-American U.S. Army sergeant.