On the eve of South Carolina’s Republican primary, presidential candidates Marco Rubio and Jeb Bush were locked in a bare-knuckled fight for third place, afraid that anything less could blunt their White House hopes.

With front-runner Donald Trump fighting to hold off U.S. Sen. Ted Cruz of Texas and win his second straight early nominating contest, Rubio and Bush are battling to become the main anti-Trump alternative among establishment Republicans seeking the party’s nomination for the Nov. 8 election.

The six remaining Republican candidates face off Saturday in South Carolina’s primary, while Democrats Hillary Clinton and Bernie Sanders will compete in the Nevada caucuses.

An NBC News-Wall Street Journal/Marist poll released on Friday showed Trump in the lead in South Carolina with support from 28 percent of likely Republican primary voters, followed by Cruz at 23 percent. Rubio led Bush narrowly, 15 percent to 13 percent.

Rubio on Wednesday was endorsed by popular South Carolina Gov. Nikki Haley, who since has been at his side on the campaign trail. That could give him a significant boost as he continues to try to recover from his fifth-place finish in New Hampshire’s primary on Feb. 9.

Bush has a key backer in South Carolina’s Republican U.S. Sen. Lindsey Graham.

The latest campaign chapter arrives with its share of twists — a staple of the 2016 presidential race. Thursday brought a rare criticism of a White House candidate by a pope.

The dispute between Trump and Pope Francis that erupted Thursday — wherein the pontiff suggested Trump “is not Christian” because of statements the billionaire made about building a wall on the Mexico border — dominated the campaign Thursday, but it wasn’t clear it would have staying power, at least in South Carolina. Catholics represented just 13 percent of state’s Republican primary electorate in 2012, according to exit polls.

Trump first called the pope’s actions “disgraceful,” but softened his tone hours later at a CNN town hall in Columbia.

“I like his personality,” Trump said. “I like what he represents. And I certainly have respect for the position.”

In another twist, Michael Bloomberg, founder and majority owner of Bloomberg News parent Bloomberg LP, elaborated at a book party Thursday on why he is considering a third-party presidential bid but announced no such candidacy.

“This really has been a race to the extremes,” Bloomberg said, according to a transcript of his remarks.

The state’s voting could spell trouble for Bush, who is trailing in the polls. He focused Friday on the northwest, the state’s conservative heart, where his mother, former first lady Barbara Bush, joined him on the trail.

Bush pitched himself as the most accomplished candidate, warned about backing a candidate who isn’t ready for the job, and criticized Trump for saying George W. Bush was responsible for the Sept. 11, 2001, terrorist attacks.

Democrats vote in South Carolina a week later, so the outcome in Nevada’s caucuses Saturday will be felt. A Clinton loss in Nevada, after a crushing 22-point defeat by Sanders in New Hampshire, would further stoke doubts about her staying power in a general election against a Republican.

At a Thursday night MSNBC town hall in Las Vegas, Clinton again confronted the issue of whether she was trustworthy. In answering a question from a Sanders supporter about when she would release the transcript of speeches she had been paid to give to large financial institutions, Clinton played defense.

“I was a candidate who went to Wall Street before the crash. I went to them and said you are wrecking our economy,” Clinton said. “I now have the most effective and comprehensive plan to deal with the threat that Wall Street poses.”

Speaking before Clinton, Sanders kept to the populist themes that have made him competitive with his Democratic rival.

“Do I believe that there has to be a major focus on the economy when the middle class is disappearing?” Sanders quipped when asked about Clinton’s critique that he was a single-issue candidate. “Yeah, I’m going to focus on that.”

Clinton has taken selfies and shaken hands with cooks, maids, housekeepers and cocktail waitresses inside the break rooms of nearly half a dozen hotels along the Strip this week in a last-minute push to boost turnout among Latino voters and to blunt efforts by Sanders to make inroads among minority Democrats.

The Latino vote will be decisive in the caucuses, said Andres Ramirez, a local Democratic strategist who is supporting Clinton, and that means turnout among members of the state’s largest union.

This week, both Clinton and Sanders visited a Culinary Union picket line over health care costs for employees.

Health care plans are an issue of concern for many union members in Nevada. In interviews, Culinary Union leaders have expressed disdain for the “Cadillac tax” in the Affordable Care Act, a 40 percent levy on certain generous employer-sponsored health coverage plans, which is set to take effect in 2020. Both candidates have said the provision should be repealed.

But Clinton has sought to cast doubt on Sanders’ credibility with unions.

Speaking at an outdoor rally before Laborers’ International Union members on Thursday night, she basked in the support she has received from nearly two dozen powerful national unions.

“It’s because I’ve worked for them, because I’ve fought for them,” she said.

Sanders, who spent Friday far from Las Vegas, with rallies in Elko and Sparks, Nevada, has benefited from the support of National Nurses United, which has held several rallies in support of his candidacy across Nevada this week.

And Culinary Union members such as Edwin Valles, a cook at Jerry’s Nugget Casino, said he’s supporting Sanders because of his tuition-free college plan.

“For a lot of kids, that would be a dream come true. Maybe I could then be able to go to school,” Valles, 24, said. “He’s caught my attention because he talks to the youth.”

Valles will vote in his first caucus Saturday.

In Valles’ conversations with co-workers and friends, Clinton is not mentioned — perhaps evidence of a generational split as Sanders appeals to younger voters.

“She’s not known,” he said of Clinton. “At least the people I know don’t know her.”