Vulnerable red-state Democrats vying for U.S. Senate seats will be attending a $2,000-per-guest fundraiser hosted by a prominent Democratic donor who called President Trump supporters “traitors,” implied conservative ideas were “low IQ” and suggested members of the GOP were members of the KKK.

Kyrsten Sinema, a Democrat running in Arizona, and Claire McCaskill, an incumbent senator in Missouri, will attend the fundraiser on Friday in Edwardsville, Ill., hosted by Jeff Cooper, a St. Louis-area litigator turned soccer executive, who attended a state dinner at the Obama White House in 2011.

The invitation for Friday's event lists Cooper and his wife Francesca as the hosts, in addition to few other hosts. It suggests contributing to McCaskill and Sinema between $2,000 and $5,400.

“To all you Trump folks out there, I hope you are proud. Traitors. All of you,” Cooper wrote in a tweet on his little-known Twitter account, the authenticity of which was confirmed by Fox News.

He also shared an article that claims “low IQ” and “conservative beliefs” are linked to people being prejudiced. “This explains it all. They really are stupid,” he wrote in another tweet.

Cooper has also compared the members of the Republican Party to the Ku Klux Klan, retweeting a post that featured an image of a KKK robe and captioned with “Friendly reminder to @GOP that it's impolite to wear your whites after Labor Day.”

The fundraiser host’s social media posts put the two U.S. Senate contenders in an awkward spot as they run as moderates in states won by Trump and try to navigate away from the partisan attacks of their bicoastal Democratic colleagues.

The campaigns for McCaskill and Sinema didn’t respond to Fox News’ request for a comment.

But despite their claims of independence, the two Democrats are running in two of the most closely watched races in these midterm elections, with McCaskill tied in polls with her Republican opponent, Missouri Attorney General Josh Hawley.

According to Fox News’ 2018 Midterm Power Rankings, the race between Sinema and Republican Martha McSally is a toss-up as well.

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Cooper and his wife’s ties to Democrats are long-documented. He used to be a name partner at the SimmonsCooper law firm, before it became Simmons Hanly Conroy, which is a top donor to McCaskill and the Democratic Senatorial Campaign Committee, donating nearly nearly $800,00 in total this election cycle.

Personally, he has given roughly $300,000 to Democrats, while his wife gave an additional $100,000, according to the Center for Responsive Politics.