Donald Trump, Jeb Bush and John Kasich fight for votes on stage in S.C.

With only two days to go before South Carolina's Republican primary, Donald Trump, Jeb Bush and John Kasich on Thursday night faced questions from the state's likely GOP voters, many of whom were undecided.

Taking the CNN town hall stage last, Trump was the one candidate who continued to attack his competitors, as well as former President George W. Bush. Meanwhile, Jeb Bush and Kasich focused on their records and policy positions.

Trump, who's been leading in South Carolina polls, went after Sen. Ted Cruz, saying "he has a problem with the truth." Trump referred to the Cruz campaign photoshopping an image of Sen. Marco Rubio shaking President Obama's hand, the false rumor the Cruz campaign spread about Ben Carson about dropping out during the Iowa caucuses and a voter violation mailer that was sent to voters in Iowa.

Host Anderson Cooper expressed skepticism that Trump would wind up suing Cruz to challenge his eligibility to be president.

"You don't know that," said Trump, who sent the Cruz campaign a cease-and-desist letter this week demanding that it pull ads using old footage of Trump talking about his previous pro-choice stance.

A voter asked Trump if he would amend his statement from the last debate that President George W. Bush lied to get the U.S. to invade Iraq.

"A lot of people agree with what I said. Nobody really knows why we went into Iraq," he said. "I'll tell you very simply, it may have been the worst decision that anybody, that any president has made, in the the history of this country."

During the town hall, Buzzfeed published a story with audio of a 2002 radio interview Trump did with Howard Stern in which he expressed support for the Iraq war. Asked for a reaction, Trump conceded, "I could have said that. I wasn't a politician....By the time the war started, I was against the war."

Trump also appeared to soften his stance on his spat with Pope Francis. Earlier in the day, the Pope suggested it was "not Christian" of Trump to propose to build a wall along the U.S. border with Mexico to stop illegal immigration. At the town hall, Trump said, "I think he was very much misinterpreted. I also think he was given false information."

Former Florida Gov. Jeb Bush took the stage and was immediately asked about the back-and-forth Thursday between the Pope and Trump. Even though the two candidates are not on the greatest of terms, Bush defended Trump.

"I don't question people's Christianity," he said. "I just don't think it's appropriate to question Donald's faith."

Bush was asked about whether he would nominate a justice to the Supreme Court to replace Justice Antonin Scalia, who died last Saturday, if he were currently president.

"I probably would," Bush said. "Whatever powers are afforded the president, the president ought to use them."

Ohio Gov. John Kasich, who arrived late to the town hall, highlighted his record and policy positions. But he also talked about voters and the personal connections he's made with them in the course of the campaign, and the importance of slowing down to listen to their problems.

His most poignant moment was when he talked about his reaction to his parents' death in an accident involving a drunk driver when Kasich was 35 years old. It's a topic he rarely used to talk about in much detail.

"It changed my whole life...I went into a black hole with just a little pin prick of light," he said. "It's really where I found the Lord," and he seemed to suggest that it was a moment that has helped him to empathize with the losses other people suffer.

Kasich suggested he would keep his presidential campaign going regardless of the results in South Carolina's GOP primary on Saturday. He said he plans to visit Vermont, Massachusetts, Virginia, Mississippi and Louisiana.

"We're going the distance, Anderson," Kasich told Cooper.

Kasich touted his record as governor of Ohio and his accomplishments in Congress. As chairman of the House Budget Committee, he was involved in balancing the federal budget in the 1990s. In order to provide that type of economic boost again, Kasich said it would require three things: regulations that don't target small businesses, tax cuts for businesses and a move to another balanced budget. He also mentioned his 18 years on the House Armed Services Committee.

Asked if he would consider anyone in the 2016 race as a running mate, Kasich named the governor of New Jersey who dropped out last week.

"I like Chris Christie very much. I like him a whole lot," he said. "He's someone who was a candidate who would be considered."

  • Rebecca Shabad

    Rebecca Shabad is a video reporter for CBS News Digital.