9:23 p.m. What did Kasich mean when he said he wanted to punch Russia in the nose?

“We have to make it clear to Russia what we expect. We don’t have to declare an enemy, rattle a sword or threaten,” he said. “We will arm the folks in Ukraine who are fighting for their freedom. They deserve it. There will be no ifs ands or buts about it.”

He also said the U.S. should consider attacks on NATO countries or Finland or Sweden an attack on the U.S.

Bush, talking about Russia, said it is “ludicrous” to consider them a partner in the fight against ISIS.

9:20 p.m. Rubio is asked what in his past he can point to as evidence to voters that he is ready to handle a crisis in office. He points to his vote against President Obama’s plan to use military force against Syrian dictator Bashar Assad.;

“One of the hardest decisions you’ll ever make in Congress is when you are asked to authorize the use of force in a conflict,” he said.

9:16 p.m. Dickerson and Cruz briefly tussle when Dickerson asks Cruz what the cutoff should be for a president selecting a justice in an election year.

“We have 80 years of precedent of not confirming Supreme Court justices in an election year,” Cruz said.

Dickerson noted that Justice Kennedy was confirmed in 1988, the last year of Reagan’s presidency.

9:12 p.m. Would Bush apply a litmus test for a Supreme Court nominee?

“Not on specific issues, not at all,” he said. He said the next president should nominate someone with a “proven record in the judiciary” as well as a proven conservative record.

He said the president has a right to nominate a justice, but said Mr. Obama would “not have a consensus pick.”

9:11 p.m. Rubio says he has never supported changing Senate rules to allow a Supreme Court justice to be nominated with a simple majority in the Senate.

9:07 p.m. The death of Supreme Court Justice Antonin Scalia just hours ago looms large over the start of hte debate. Moderator John Dickerson asks Trump to consider himself in President Obama’s shoes: If he were president, wouldn’t it be an “abdication to conservatives” if he did not nominate someone — as Trump has called on Obama to do?

“If I were president now I would certainly want to try to nominate a justice,” Trump said. But he added, “I think it’s up to [Senate Majority Leader] Mitch McConnell and everybody else to stop it, it’s called delay, delay, delay.”

McConnell has said the Senate should wait for the next president to nominate someone.

Kasich said he wished the president would consider not nominating someone, or only nominating a person who has near-universal support.

8:45 p.m. The six remaining Republican presidential candidates are about to take the stage in Greenville, South Carolina for their first debate since this week’sNew Hampshire primaries.

This is last debate before South Carolina’s Republican primary on Feb. 20. It begins at 9 p.m. and ends at 11 p.m. ET.

The candidates who are participating include businessman Donald Trump, Texas Sen. Ted Cruz, Florida Sen. Marco Rubio, former Florida Gov. Jeb Bush, former neurosurgeon Ben Carson, and Ohio Gov. John Kasich.

Since the New Hampshire primaries, former tech executive Carly Fiorina, New Jersey Gov. Chris Christie, and former Virginia Gov. Jim Gilmore have withdrawn from the race.

“Face the Nation” host and CBS News political director John Dickerson is serving as the main moderator for the debate. He will be joined by two panelists: CBS News chief White House correspondent Major Garrett and The Wall Street Journal’s Kimberly Strassel.

CBS News will offer multi-platform coverage of the debate, with extensive coverage before, during, and after the debate via CBSN, the network’s 24/7 digital streaming news service.

CBSN is also offering a special 9:00 PM broadcast of the debate that will include enhanced graphics to showcase real-time Google Trends data and a curated Twitter stream.

To catch a preview of Saturday’s debate stage, take a look at this 360-degree view of the stage, taken from Donald Trump’s center podium.