Kyle Rittenhouse faced backlash from MAGA after supporting anti-Trump Republican Congressman Thomas Massie in one of the GOP's nastiest primary battles.

Rittenhouse, a conservative activist, was once celebrated across pro-Trump media after being acquitted in the 2020 Kenosha shootings.

But he suddenly found himself under attack from prominent MAGA influencers after campaigning for Massie ahead of Kentucky's high-stakes Republican primary on Tuesday.

The uproar came after Rittenhouse appeared at a 'day at the range' event in Burlington, Kentucky, where he enthusiastically endorsed the libertarian-minded congressman.

'Thomas Massie is the greatest congressman, I believe, in a very long time,' Rittenhouse told supporters at the event.

Rittenhouse dismissed criticism aimed at the Kentucky Republican.

'He supported me from the beginning, and a lot of things that are being told about him are lies, not true,' he said.

But Donald Trump has made Massie one of his top political targets. The endorsement instantly placed Rittenhouse on a collision course with Trump and some of his most loyal online supporters.

The backlash against Rittenhouse online was immediate and brutal, with some MAGA personalities turning on the activist they once championed.

'Wow! Kyle Rittenhouse turned out to be a complete d*****bag, we should've left him to the liberal wolves in 2020!' wrote MAGA commentator Vince Langman on X.

Rittenhouse responded by posting a screenshot of an older Langman post praising him as 'a true American hero.' He added: 'LOL.'

Other pro-Trump accounts piled on.

'Screw that pasty doughboy. His 5 minutes of fame are over,' one critic wrote online. 'He supports Massie says all you need to know.'

Another user mocked Rittenhouse's failed attempts to join law enforcement.

'He was literally too low IQ to join the military or police. This kid is a loser,' a post read.

Some former Rittenhouse supporters openly announced they were abandoning him politically over the Massie endorsement.