The 'Real Time' host said Donald Trump may be old, but he's a dog always in search of women, and Bill said there are breadcrumbs of evidence leading him to Laura Loomer -- as he says, she's 31 and Trump's "type."

Well, B.M. noted she's been like white on rice with Trump recently, which then raised a question for him ... "Who's Trump f***ing? Because I said, 'it's not nobody.' He's been a dog for too long. And it's not Melania. I think we may have our answer this week."

Loomer immediately fired back, threatening to sue Bill, saying, "I should sue @billmaher for Defamation. This is beyond the pale and it’s a complete and blatant lie. I have never in my life seen such a coordinated attack by the mainstream Media, the White House and leftist personalities to target a private citizen and  investigative journalist simply because I flew on a plane and I support Donald Trump.  This is unacceptable. And it’s a full blown LIE and incredibly disrespectful to President Trump and First Lady Melania Trump."

BTW ... Loomer weighed in on another relationship, calling the one with Taylor Swift and Travis Kelce "arranged" to influence the election.

As for Loomer's politics, let's just say she's WAAAAAY to the right of Marjorie Taylor Greene. Among some of her racist comments, just shy of the debate she posted on X ... if Harris, whose mom was Indian American, got elected, the White House would "smell like curry."

Trump has not commented yet, but that's sure to follow.