(CNN) Roy Moore is (probably) running for the Senate again in 2020. Which is an absolute dumpster-fire scenario for Senate Republicans trying to keep their majority next November.

Here's where we stand: Rep. Bradley Byrne (who is already running for the chance to take on Alabama Democratic Sen. Doug Jones next year) said Tuesday that he expected Moore to run.

In response, the former Senate candidate and state Supreme Court justice tweeted this challenge : "What is Bradley so worried about? He knows that if I run I will beat Doug Jones."

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Moore, who lost to Jones in a 2017 special election, followed that up with this tweet on Wednesday: "Ever wonder why the mere mention of my name scares the 'hell' out of the Washington DC establishment, liberals, and LGBT? Like Pres Trump I want to see America great again, but that is a job only God can do!"

Riiiiight.

Let's remember that Moore lost to Jones in a special election occasioned by Jeff Sessions' appointment as attorney general in the Trump administration. In Alabama. A state where President Donald Trump won by 28 points just a year prior. And Moore lost that race because a series of women came forward to allege that he had pursued sexual relationships with them as teenagers , when Moore was in his 30s. (Moore repeatedly denied all of the allegations against him and, somehow, blamed the media for them. He later sued three of the women, alleging a "political conspiracy," and that legal battle is still being fought.)

It was, by all accounts, a disastrous campaign run by a deeply out-of-touch and deluded candidate who refused to acknowledge the depths of his political flaws. Which everyone in the GOP acknowledges -- except Roy Moore and his very committed band of longtime supporters.

Which brings us to the nub of this Republican nightmare: Moore could actually beat Byrne in a Republican primary, a victory that would likely, again, cost GOPers a Senate seat they should absolutely, on paper, hold.

Recent history speaks to the problem. Moore knocked off appointed Sen. Luther Strange in the special Republican primary, despite the fact that Strange had the support of, among others, Trump and Senate Majority Leader Mitch McConnell (Ky.). McConnell and others warned Alabama Republicans that nominating the deeply divisive Moore -- and this was before the allegations of sexual misconduct emerged -- was a major risk for the party, and one that could mean they would lose the seat.

Moore's voters didn't care. They had been with him since (or probably before) he drew national headlines for having a Ten Commandments statue installed in the state Supreme Court . (Moore was removed as chief justice of the court when he refused to take the statue down .) His supporters viewed him as a warrior against PC culture, against the political class, against liberals. That Trump and McConnell wanted the guy he was running against played perfectly into the us-against-the-world mentality that Moore cultivated.

None of that -- or very little of it -- has changed for Moore. Losing to Jones didn't dull the ardor of those who are for more through thick and thin. In fact, it might have even increased their passion -- proving that the "establishment" would do whatever it took to keep Moore from office. And they might relish another chance to show Republican bigwigs in Washington just what they think of them.

National Republicans -- led by McConnell -- understand the threat that Moore poses to their chances of beating Jones. Which is why on Wednesday morning, President Donald Trump took to Twitter to dissuade Moore from a candidacy.

"Republicans cannot allow themselves to again lose the Senate seat in the Great State of Alabama," Trump tweeted . "This time it will be for Six Years, not just Two. I have NOTHING against Roy Moore, and unlike many other Republican leaders, wanted him to win. But he didn't, and probably won't."

(Trump's tweet echoed one by his son, Don Jr., on Tuesday night; "You're literally the only candidate who could lose a GOP seat in pro-Trump, pro-USA ALABAMA," Trump Jr. tweeted . "Running for office should never become a business model. If you actually care about #MAGA more than your own ego, it's time to ride off into the sunset, Judge.")

Maybe the words of Trump -- or Trump Jr. -- will resonate with Moore, and he will change his mind from what looks like a near-certain bid for Senate. But if past is prologue -- and it almost always is, since we humans don't change all that much -- Moore ain't changing course. He's running -- and Republicans need to hope like hell he doesn't win the nomination again. If he does, the party can say "so long" to the seat for six more years.