A lame-duck Republican U.S. senator from Tennessee has weighed in with an interesting — but possibly worthless — conjecture about Donald J. Trump’s political future.

Bob Corker — who has announced his intention to retire at the end of the year — has said it is not a “sure thing” that the president will seek re-election in 2020, even though he has formed a committee and has begun raising money for an expected effort at winning a second term.

I won’t comment on whether Corker knows something no one else on Earth knows. He does pose an interesting notion.

Consider what might be coarsing through the president’s self-acknowledged ample brain.

• He is facing a possible “blue wave” election later this year, with Democrats taking control of the U.S. House and the U.S. Senate. That means he could become the third president ever impeached by the House of Representatives. I am not going to bet the farm that a Senate controlled by a slim Democratic majority would convict him.
• Trump also might face a primary challenge in 2020. There could be any number of Republicans who are furious enough with the president to challenge him in two years. They could draw substantial political blood in the process.
• The president might have to watch every single legislative agenda item on his to-do list stalled over the “Russia thing,” the porn queen scandal, the nagging tempest over his business dealings.

What in the world might that portend if hell freezes over and he actually is re-elected in November 2020?

Does the president really want to subject himself to the humiliation that might await him? I mean, he is a narcissist extraordinaire. It’s all about him as president, just as it was all about him as reality TV celebrity and business mogul.

This is the payback that well might await a man who built his entire pre-politics reputation on self-enrichment and self-aggrandizement. Public service was never part of his modus operandi.

Might he decide to bail after one term? I have no idea. My hope is that he calls it a career. But with Donald Trump, well, one never can predict a single thing.