Following a bloodbath for Republicans in the 2018 midterms, then-House speaker Paul Ryan couldn’t believe what he had seen out in California.

“We were only down 26 seats the night of the election and three weeks later, we lost basically every California race,’’ Ryan — a mentor to California Republican and current House GOP head Kevin McCarthy — told the Washington Post in a post-mortem interview. “This election system they have — I can’t begin to understand what ‘ballot harvesting’ is.”

Ryan’s disbelief was prompted by a “blue tsunami” of mail-in ballots that tipped early-GOP leads and cost California Republicans seven seats when …