A conservative Super Pac will pour money into Arizona to support Blake Masters, the Republican US Senate candidate whose extreme views have raised alarm among Democrats but also hopes, backed by polling, that independents and moderates will not vote for him in November.

Politico reported on Monday that Sentinel Action Fund will spend at least $5m to back the Trump-endorsed candidate against the Democrat Mark Kelly, the former astronaut turned gun control campaigner who holds the Senate seat.

Like other Trump-backed candidates in crucial states, Masters has struggled in public polling. On Monday, less than two months out from election day, fivethirtyeight.com gave Kelly a six-point lead and a 74% chance of victory.

Masters, 36, is an author and venture capitalist with close ties to the billionaire tech investor and Trump donor Peter Thiel.

Among controversial statements, Masters has blamed gun violence on Black people; said Democrats are trying to “change the demographics of this country”; and claimed Kamala Harris was only picked to be vice-president because of her race and gender.

He has also been dogged by reporting of views he expressed as a student, including advocating for open borders and saying the US should not have entered either world war, although the second was “harder to argue because of the hot button issue of the Holocaust”.

Reporting a new batch of emails, HuffPost.com said that while a student at Stanford University, Masters said America was fascist.

The report dropped amid Republican anger over Joe Biden’s warnings that US democracy is threatened by “semi-fascist” supporters of Donald Trump.

The Senate is split 50-50 but controlled by Democrats through the vote of the vice-president, Harris. Like Ohio, Georgia and Pennsylvania, Arizona is widely seen as a battleground state which could tip the chamber.

Jessica Anderson, president of Sentinel Action Fund, told Politico: “Arizona is the center of the fight for America’s soul. It is time for every corner of the conservative coalition to deploy every resource to win the Senate and show up to support our conservative candidates like Blake Masters.”

HuffPost reported a newly unearthed batch of emails sent to members of “a left-leaning vegan co-op … where Masters lived” while at Stanford. In the emails, Masters said it was legitimate to be skeptical about the “official story” of the 9/11 attacks, flirted with antisemitism when discussing why America entered the first world war, and said voting was pointless and often immoral.

In January 2006, when the White House and Congress were in Republican hands, Masters also composed an email entitled “Fascism + America = right now”.

Linking to a blogpost now not available online, he wrote: “The thesis is that the United States government is fascist. I hope that you find the analysis interesting and illuminating. If only one person reads it, it will have been a well-spent Friday night.”

Masters’ campaign declined to comment but he has discussed his student writings. During the primary, on social media, he criticised a Republican opponent’s use of such emails but also said: “The leftwing media, of course they’d try to smear me. We knew they were going to try to call me a racist and a sexist and a terrorist.”

The party which does not control the White House usually does well in the first midterms of a president’s time in office. This year, however, Democrats hope factors including Trump and the supreme court removing the right to abortion can propel the party to victory.

Earlier this month, Barbara Comstock, a former Republican congresswoman, told NPR the party’s struggles in key Senate races were in large part the result of being beholden to Trump.

“I think the longer the party stays enthralled to him and tied to him,” she said, “the longer the party is going to be losing in the long term.”