“Last Week Tonight” host John Oliver said on Sunday that Fox News host Sean Hannity had come up with the worst conspiracy theory ever to defend President TrumpDonald John TrumpLondon terror suspect’s children told authorities he complained about Trump: inquiry The Memo: Tide turns on Kavanaugh Trump to nominate retiring lawmaker as head of trade agency MORE.

Hannity, in discussing the infamous 2016 Trump Tower meeting between Trump campaign officials and a Russian lawyer they'd been told could offer damaging information on then-Democratic presidential nominee Hillary ClintonHillary Diane Rodham ClintonHillicon Valley: Trump's exclusive interview with Hill.TV | Trump, intel officials clash over Russia docs | EU investigating Amazon | Military gets new cyber authority | Flynn sentencing sparks new questions about Mueller probe READ: President Trump’s exclusive interview with Hill.TV Keeping up with Michael Avenatti MOREreferenced on his show this past week a May 18 Daily Caller story that said a Russian-American lobbyist who participated in the meeting claimed to personally know Clinton.

“So let me get this straight: You seem to be implying Hillary Clinton sent someone into Trump Tower to offer her opponent dirt on herself,” Oliver said. “You know what? Congratulations, Sean Hannity, you’ve officially come up with the shittiest conspiracy theory ever.”

Oliver went after Republicans for trying to diminish public opinion of special counsel Robert MuellerRobert Swan MuellerSasse: US should applaud choice of Mueller to lead Russia probe MORE’s investigation into possible Russian collusion.

“They aren’t really interested in getting to the bottom of any of these questions, they’re trying to sow enough doubt that this number dips far enough below 50 percent to allow the whole investigation to be shut down. They are just working the jury,” Oliver said.

The Russian lobbyist Hannity mentioned reportedly told the Senate Judiciary Committee that he had contact with Clinton’s inner circle and that he knew the then-candidate as well.

“I knew [Clinton]; I knew some people who worked on her campaign,” Rinat Akhmetshin said in closed-door testimony in November, according to The Daily Caller.

The Trump Tower meeting took place after Rob Goldstone, an associate of Donald Trump Jr.Donald (Don) John TrumpFlake condemns Trump Jr. Instagram post mocking Kavanaugh accuser Trump Jr. campaign event looks for new venue after Montana restaurant declines to host The Hill's 12:30 Report — Kavanaugh controversy consumes Washington | Kavanaugh slated to testify Monday | Allegations shake up midterms MORE, told him that a Russian government attorney, now identified as Natalia Veselnitskaya, had dirt on Clinton.

“If it is what you say, I love it,” Trump Jr. wrote to Goldstone.

Akhmetshin attended the Trump Tower meeting with Veselnitskaya and is a person of interest in the investigation into possible collusion between Russia and the Trump campaign.