Las Vegas (AFP) - Russian espionage claims and attacks from rivals were shrugged off by supporters of Bernie Sanders as the Vermont senator galvanized crowds for the latest Democratic presidential nomination vote.

On a cold and wintry Friday night at the Nevada nature center, where Sanders hosted his final rally a day before the desert state's caucuses begin, the audience's fanatical faith in the leftist firebrand was palpable.

James Jones, born and bred in gambling mecca Las Vegas, said his father would still be alive instead of succumbing to a terminal illness last year had Sanders been elected to the White House during his earlier campaign in 2016.

"My dad was unable to work and was uninsured. It was too expensive to get him on my mom's health care under her plan, and he passed away last year," said the Walmart employee.

"So I feel, honestly at the bottom of my heart, that Medicare For All would have saved him," Jones added, referring to the Democratic frontrunner's signature healthcare policy.

Hours earlier, Sanders was hit with revelations from US officials that Russia -- which interfered in the 2016 elections in a bid to boost Donald Trump -- was actively trying to help his own presidential bid.

This information, and Sanders' swift rebuttal, appeared to have only strengthened convictions.

"Bernie's not gonna allow it," said military veteran Brenda Bolton, 67. "He doesn't want interference -- Trump does, Trump welcomes it."

"It speaks a lot that the day before the Nevada caucus, it just so happens that there's information leaks," added 23-year-old Jones, in a conspiratorial tone.

"There's a lot of shady stuff happening."

Nevada polls indicate that Sanders' support is growing -- he has surged to a double-digit lead in the contest.

- Double-digit lead -

Sanders was in high spirits as he took to the stage at the natural amphitheater, backed by a sheer rockface with the candidate's silhouette projected on its side.

He was preceded by a folk band sporting hipster haircuts and wide-brimmed hats, as well as a series of guest speakers who ripped into criticisms from rival Democratic contenders that Sanders' supporters are misogynistic, or his policies too far-left.

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"This is not a campaign of 'bros,'" declared author Naomi Klein.

"It's not radical, it's right on time," added former Ohio senator Nina Turner.

There was one apparent reference to the Russia revelations -- but it focused on the intelligence chief sacked after his staff briefed Trump about Moscow meddling to support him.

"We cannot continue having a president who is a bully, who can't even get along with people that he appointed... every other day he's firing somebody," said Sanders.

Two thousand supporters confidently cheered the senator's policies on healthcare, climate change and gun control -- and booed a mention of Democratic rival Michael Bloomberg's multi-billion-dollar fortune.

Michael Shackleford, a 54-year-old actuary introducing his young daughter to politics, said he wasn't sure which candidate had the best chance of defeating Trump in November.

"But I like Bernie better," he said. "It's that simple."