A day after calling him a "major, major, major sleaze," Donald Trump thanked disgraced former New York Rep. Anthony Weiner for helping to reopen the case into Democratic rival Hillary Clinton's private email server.

"We never thought we were going to say thank you to Anthony Weiner," the Republican nominee said at a rally in Las Vegas on Sunday. The crowd burst into cheers.

The FBI announced Friday that it is reopening the Clinton case after investigating Weiner for a sexting scandal he was involved in with a number of women.

A laptop owned by Weiner was found to contain over 1,000 emails deemed pertinent to the case involving Clinton's use of a private server to handle confidential communications while she was secretary of state.

"Hillary has nobody but herself to blame for her mounting legal problems," Trump told the crowd in Nevada. "Her criminal action was willful, deliberate, intentional and purposeful," he said, even though the FBI has not shared what the emails show.

"She set up this illegal server knowing full well that her actions put our national security at risk," along with the "safety and security of your children," Trump continued.

FBI Director James Comey initially closed the investigation in July after finding no evidence to recommend criminal charges be leveled against Clinton.

Trump believes the investigation has been "rigged" by U.S. Attorney General Loretta Lynch, who he claims is putting pressure on Comey to bury the investigation.

Reports on Sunday show that FBI agents had kept the Weiner emails under wraps since Oct. 2 before deciding on Thursday to brief the director on what they found. Comey has faced broad criticism by Democrats for telling Congress on Friday that the investigation was being reopened only 11 days before a presidential election.