A back-bench congressional Democrat has issued a warning to the president of the United States.

Rep. Ted Lieu says Congress will start impeachment proceedings if Donald J. Trump fired special counsel Robert Mueller and the fellow who picked him for the job, Deputy U.S. Attorney General Rod Rosenstein.

Message to the president? Don’t even think about it.

I’m not yet sure how Rep. Lieu knows what the House leadership would do. It’s run by members of the other party. Republican House Speaker Paul Ryan would be the key member to set impeachment proceedings into motion. I am not yet convinced Ryan has the fortitude to do the right thing if Trump were to commit what could be considered an impeachable offense.

I also have mixed feelings about an impeachment in the first place.

It’s clear to you, I am sure, that I don’t believe Trump is fit for the office to which he was elected. What would we get if Trump were impeached and then convicted in a Senate trial? Vice President Mike Pence is more of a “true conservative” than Trump. He seems competent enough, whereas Trump can’t find his backside with both hands when it comes to understanding the complexities of government.

OK, I didn’t support the Republican ticket in November 2016. I do take some solace, though, in realizing that I am a member of a majority of voters who endorsed the other major-party candidates.

But … back to my point about impeachment.

We’re a long way from even thinking about that — unless the president does something seriously foolish by firing Mueller and Rosenstein.