As Democrats in Nevada went to the polls on Saturday, Donald Trump gleefully stirred the pot over reports that US intelligence believes Russia is trying to aid Bernie Sanders, the frontrunner for the nomination to face the president in November.

In a tweet, Trump said: “Democrats in the Great State of Nevada (Which, because of the Economy, Jobs, the Military & Vets, I will win …) be careful of Russia, Russia, Russia.

“According to Corrupt politician Adam ‘Shifty’ Schiff, they are pushing for Crazy Bernie Sanders to win. Vote!”

US intelligence has determined that Russian interference in the 2016 US elections not only supported Trump but included efforts to boost Sanders in his bitter primary against the eventual Democratic nominee, Hillary Clinton.

On Thursday, the Washington Post reported that the House intelligence committee had been briefed that Russia was once again trying to interfere in favour of Trump.

Schiff is the Democratic chair of that committee and as a leading figure in Trump’s impeachment over his approaches to Ukraine has become a regular target for presidential vitriol.

Reports about the briefing described a furious reaction from Trump which led to the departure of Joseph Maguire, the acting director of national intelligence, and his replacement by a Trump loyalist, the ambassador to Germany, Richard Grenell.

On Saturday, ABC News released an interview in which Robert O'Brien, Trump's fourth national security adviser, said he had not seen “any intelligence that Russia is doing anything to attempt to get President Trump reelected”.

On Friday, the Post reported that Sanders, Trump and “lawmakers on Capitol Hill” had been briefed about “Russian assistance to the Vermont senator” this year, but said it was not clear what the effort involved.

In a statement, Sanders said: “I don’t care, frankly, who [Russian president Vladimir] Putin wants to be president. My message to Putin is clear: Stay out of American elections, and as president I will make sure that you do.

“In 2016, Russia used internet propaganda to sow division in our country, and my understanding is that they are doing it again in 2020. Some of the ugly stuff on the internet attributed to our campaign may well not be coming from real supporters.”

In Nevada, “ugly stuff” attributed to Sanders supporters has included abuse aimed at female leaders of the Culinary Workers Union, an influential presence in the state which opposes the Vermont senator’s plan for Medicare for All healthcare reform.

Nonetheless, Sanders seems set to win. On Saturday morning the realclearpolitics.com polling average for Nevada put the progressive star 16.5 points up on two moderates, Pete Buttigieg and Joe Biden.

Nationally, Sanders leads the same site’s average by 11.4 points, over Biden and the former New York mayor Mike Bloomberg, who is not competing in Nevada.

Some suggest Trump wants to face Sanders at the polls, rather than Biden or Bloomberg.

Rick Wilson, a former Republican consultant turned author and ardent Trump critic, recently told the Guardian that Sanders, a self-described democratic socialist who sits in the Senate as an independent, would be “the easiest person in the world to turn into the comic opera villain Republicans love to hate, the Castro sympathiser, the socialist, the Marxist, the guy who wants to put the aristos in the tumbril as they cart them off to the guillotine”.

The special counsel Robert Mueller’s investigation of Russian interference in the 2016 election did not establish a conspiracy between the Trump campaign and Moscow but did lay out extensive contacts and numerous instances in which the president seemed to seek to obstruct the course of justice.

Trump has claimed vindication but the investigation remains a running sore and at a campaign rally in Las Vegas on Friday, he duly took aim at his political opponents.

“I see these phoneys, the do-nothing Democrats,” Trump said. “They said today that Putin wants to be sure that Trump gets elected. Here we go again. Here we go again. Did you see it? ... Now I just see it again. I was told that was happening, I was told a week ago. They said you know they’re trying to start a rumor. It’s disinformation.”

In tweets and retweets after the event, the president loosed off shots at another favourite target, the media.

Referring to MSNBC as “MSDNC (Comcast Slime)”, he said that network and CNN “and others of the Fake Media, have now added Crazy Bernie to the list of Russian Sympathizers, along with Tulsi Gabbard [and] Jill Stein (of the Green Party), both agents of Russia, they say.”

Gabbard, a Hawaii congresswoman still in the running for the Democratic nomination but not registering significantly in the polls, has sued Hillary Clinton for allegedly calling her a “Russian asset”.

Stein was the Green nominee for president in 2016, taking nearly 1.5m votes nationally (while the Libertarian Gary Johnson took more than 4m) in a contest Clinton won by nearly 3m. Trump took the White House in the electoral college.

Clinton beat Trump by two points in Nevada, a key swing state again this year.

On Twitter, Trump claimed the reason for media reports that “President Putin wants Bernie (or me) to win … is that the Do Nothing Democrats, using disinformation Hoax number 7, don’t want Bernie Sanders to get the Democrat Nomination, and they figure this would be very bad for his chances.

“It’s all rigged, again, against Crazy Bernie Sanders!”

