Growing numbers of Democrats regard Bernie Sanders as their best bet in defeating President Donald Trump in his re-election campaign.

Mr Sanders's dominating performance in last week's Nevada caucuses, powered by growing support across age, race and ideology, has set off alarm bells among Democratic Party officials who believe putting the progressive stalwart at the top of the ticket will harm the party's chances up and down the ballot.

His electability was a prime topic at Tuesday's Democratic presidential debate in South Carolina. Rivals have argued his ambitious liberal policy ideas, such as Medicare for all, which would replace private health insurance, would be an electoral "catastrophe", costing the party the White House and control of Congress.

However, latest Reuters/Ipsos polling shows Mr Sanders is actually gaining momentum in the race - a near win in Iowa, a narrow victory in New Hampshire and a decisive win in Nevada. The victories have given him more credibility with Democratic voters.

Some 26pc of Democrats and independents polled in the past week said they now believed Mr Sanders was the strongest Democrat in a head-to-head contest with Mr Trump, compared with 20pc who picked billionaire businessman Michael Bloomberg and 17pc who named former vice-president Joe Biden.

That was a big change from a month earlier, when 27pc gave Mr Biden the edge, and only 17pc thought Mr Sanders could beat Mr Trump.

In the Nevada caucuses, Mr Sanders won the support of a majority of Latino voters and led among most demographic groups broken down by gender, income and political leanings in Nevada. Notable exceptions were those aged 65 years and older, as well as black voters, more of whom supported Mr Biden.

That too could be changing. The same Reuters/Ipsos polling showed Mr Sanders had overtaken Mr Biden in support among black voters nationally for the first time.

Saturday's South Carolina primary will be the first major test of Mr Sanders's appeal among African-American voters, who represent about 60pc of its Democratic electorate.

Three days later, 15 states or territories will cast ballots on Super Tuesday, when Mr Sanders could build an overwhelming advantage if he captures the lion's share of the available delegates.

His path has been smoothed by fragmentation among moderate candidates. Mr Biden, former South Bend, Indiana, mayor Pete Buttigieg and Senator Amy Klobuchar - who all say Mr Sanders's policies are too radical to win in November - have each recorded at least one top-three finish so far, while Mr Bloomberg's name will appear on ballots for the first time on Super Tuesday.

Mr Sanders argues the enthusiasm powering his campaign will lead to record turnout in November, particularly among young and infrequent voters, making up for any deficiency among swing voters.

"A large voter turnout would mean down-ballot Democrats will do better than they have in the past," he said. "Our campaign is the campaign to do that. We have the energy, we have the excitement, we have the grassroots movement."

At Tuesday's debate, he said the biggest misconception about him, "and you're hearing it here tonight, is that the ideas I'm talking about are radical. They're not. In one form or another, they exist in countries all over the world".

He added: "Healthcare is a human right. We have the necessity, the moral imperative, to address the existential threat of climate change. Other countries are doing that."

Results in Iowa, New Hampshire and Nevada have not provided evidence of a massive turnout surge, but Mr Sanders's fortunes have improved with each succeeding state contest.

"If you want to win in red and purple places, the most important thing you need is people who like you or who are willing to fight for you," said Senator Kirsten Gillibrand, who ended her own presidential bid last year. "You need passion, and what Bernie showed so far is that he's got a lot of passion in his campaign."

After gaining a majority in the US House of Representatives in 2018, dozens of Democrats will be defending seats in Republican-leaning areas. Several moderate Democrats have openly fretted that Mr Sanders at the top of the ticket would risk flipping those seats.

"I hear from constituents that they are afraid they are going to have a make a choice between a self-described socialist and an aspiring dictator," said US Representative Stephanie Murphy, co-chair of a congressional coalition of moderate Democrats, referring to Mr Sanders and Mr Trump. "That's not a choice any American should make."

Irish Independent