Hunter Biden says some of the biggest Republicans in Washington might be closeted ... and he's kinda naming names.

Joe Biden's son sat down with Don Lemon to dish about why conservative politicians are so obsessed with gay people ... claiming it's because they're gay, too!

Don asks Hunter point-blank if the late Lindsey Graham was part of the so-called closeted cabal. HB said it wasn't a secret, noting "everybody knew."

As far as the rest of the list ... Hunter tries not to name names -- though he did bring up a backdoor route to mention a few prominent members of the Republican Party.

Hunter didn't come out and say Senator Josh Hawley, Trump deputy chief of staff for policy Stephen Miller and Speaker of the House Mike Johnson are in the closet ... but bringing their names into the conversation in a roundabout way will certainly raise eyebrows.

HB joked he was already knee-deep in enough lawsuits ... but he might be inviting some more here.

Bottom line ... that "G" in GOP might stand for "gay" these days -- at least if you believe Hunter and Don!