For a liberal Democrat and a conservative Republican, Jersey Sen. Bob Menendez and New York Rep. Chris Collins have a lot in common — namely, huge ethical problems that they’re hoping the voters will ignore for the sake of ideology.

Menendez’s corruption is indisputable: He took six-figures gifts and donations from his “friend,” Dr. Salomon Melgen — and in exchange intervened with federal regulators who were trying to stop Melgen’s Medicare fraud. He also arranged visas for a host of the doctor’s “girlfriends.”

A hung jury saved Menendez from being sent to federal prison, but his peers in both parties on the Senate Ethics Committee declared that he’d broken the law. Most other Jersey electeds refuse to campaign with him.

After his arrest on federal securities-fraud and insider-trading charges this summer, Collins suspended his campaign and looked set to drop out. Instead, he plainly decided to try to keep his seat for use as a bargaining chip with prosecutors.

These two beauties share something else: The Post has endorsed their challengers, Republican Bob Hugin in New Jersey and Democrat Nate McMurray in New York’s 27th Congressional District.

Sadly, polls show each incumbent with a narrow lead: Partisan loyalties (blue in Jersey, red in Western New York) may save them.

Here’s the thing: If voters won’t say no to corruption and embrace honest moderates like Hugin and McMurray, US politics will continue to spiral down into the sewer.

Don’t hold your nose just because a candidate is waving the right ideology around — don’t vote for a crook who plainly holds you in contempt.