Afp, Las Vegas
From glitzy Las Vegas casinos to dusty desert crossroads, Nevada Democrats were set to vote yesterday for who should challenge President Donald Trump in November's election, with leftist firebrand Bernie Sanders riding high in the saddle.

The western state, home to three million people, is the third contest in the race for the Democratic presidential nomination.

Nevada's vote may serve to entrench Senator Sanders's status as frontrunner before the deluge of "Super Tuesday" on March 3, when people in 14 states troop to the ballot box.

Or it could provide a much-needed boost for one of the moderate candidates desperate to halt his rise.

On the eve of the vote, Sanders was hit with published revelations from US officials that Russia -- which interfered in the 2016 US elections in a bid to boost Trump -- was actively trying to help his own presidential bid.

Sanders immediately rejected any help that might come from Vladimir Putin's government or allies, instructing the Russian president to "stay out of American elections."

The Democratic race is entering an urgent phase. Any momentum from results in Nevada, and then South Carolina which votes on February 29, could prove decisive, while poor showings are almost certain to close the door on some campaigns.

Of the eight contenders still seeking the Democratic presidential nomination, Sanders leads in polling in Nevada and nationally by about a dozen points over second-place Biden.