DES MOINES, Iowa (Reuters) - Bernie Sanders got a taste of life as a front-runner in the spotlight at the Democratic presidential debate in Iowa, facing new scrutiny for his liberal views and questions about whether he can beat President Donald Trump in November.

The attention was an acknowledgment of Sanders’ steady rise to the top of some opinion polls in the early nominating states of Iowa and New Hampshire. Now the progressive standard-bearer faces the hard work of turning his core of fervent support into election wins.

The first contests in the Democratic race to find a challenger to Trump will begin to show how far Sanders can go with his message of standing up to corporate interests, reducing income inequality and expanding benefits for the poor and working class. The nominating process kicks off in Iowa on Feb. 3.

Sanders has strong support among young and liberal voters and those without a college degree. Many polls show the U.S. senator from Vermont has built a lead among Hispanics and pulled into second behind rival Joe Biden, the former vice president, among African Americans, a vital Democratic voting bloc.

The Sanders campaign also is targeting infrequent and new voters who have not regularly participated in politics but are drawn to his economic message as a way to expand its base.

“That’s the challenge for Bernie, to prove he is someone who can be a real coalition-builder and lead a party,” said Joel Payne, a Democratic strategist who worked for Hillary Clinton in 2016.

Sanders’ upstart presidential bid in 2016 battled establishment front-runner Clinton all the way to the end in that nominating race, pushing her sharply to the left and establishing him as a leader in the party’s resurgent progressive wing.

This time around, polls show Sanders in a tight fight for the lead in Iowa and New Hampshire with establishment rival Biden, fellow progressive U.S. Senator Elizabeth Warren and centrist Pete Buttigieg, the former mayor of South Bend, Indiana.

The Tuesday debate reflected Sanders’ status as one of the leaders of the pack. The democratic socialist, who had rarely come under fire even during the most contentious debates, took the majority of the heat from his rivals this time.

FILE PHOTO: Democratic U.S. presidential candidate Senator Bernie Sanders hosts a climate rally with Rep. Rashida Tlaib and Rep. Ro Khanna in Iowa City, Iowa, U.S. January 12, 2020. REUTERS/Scott Morgan/

He was put on the spot in an exchange with his friend and ally Warren, who says he told her in a private 2018 meeting that a woman could not win the White House against Trump in 2020. Sanders denied the assertion as “incomprehensible.”

He also faced criticism for his opposition to free-trade pacts and on how he would pay for his costly Medicare for All plan, which would all but eliminate private health insurance in exchange for a single-payer government program.

DEMOCRATIC SOCIALISM

Asked during the debate about polls that show up to two-thirds of voters are not enthusiastic about voting for a democratic socialist, Sanders said it would not be a problem. He pointed out that Trump practiced his own brand of socialism, taking hundreds of millions of dollars in tax breaks and subsidies when he was a real estate developer.

“We are going to take on the greed and corruption of the pharmaceutical industry and the insurance companies. That is what democratic socialism is about, and that will win this election,” Sanders said.

Sanders frequently exhorts young people, who do not vote as regularly as the elderly, to make sure they vote or caucus. He says if young Americans voted at the same rates as their elders, “we could transform this country.”

Sanders has the money to fight to the end again this time, regularly beating his rivals in fundraising last year. But for Democrats desperate to find the right candidate to beat Trump, electability may be one of Sanders’ toughest hurdles.

“He has built a remarkable campaign and done a good job of keeping his support together from 2016,” said Grant Woodard, an Iowa lawyer and former Democratic political operative in the state. “The question was always how much of his support was with him, and how much of it was against Hillary. We don’t know.”

Lynn Muhs, a retired accountant, said she had been considering backing Warren but was leaning toward Sanders after seeing him speak with “clarity” at a rally in Newton, Iowa, before the debate.

“There was no question about where he stood on the issues, and he had a clear vision of the direction he wants to go,” Muhs said.

But Linda Coen, who stood at the edge of the event in Newton with her arms crossed, said she was leaning toward Biden or U.S. Senator Cory Booker, who later dropped out.

She liked Sanders’ upfront style but said he was “too far to the left.” She also said she disagreed with his Medicare for All plan to force people from private insurance onto a government-run plan.

“I’d like to have a choice,” she said.