A government shutdown would be a disaster for Republicans. And they might not be able to stop it.

It's hard to overstate how massive a political disaster shutting down the federal government over funding (or lack thereof) for a border wall would be for Republicans.

Consider:

The GOP controls the White House as well as both chambers of Congress. Voters know this. Large majorities of the public don't believe building a wall is the solution to the country's immigration problems -- and most never believed President Donald Trump's much-promised wall would get built in the first place. Six in 10 people in a recent CBS News poll opposed building the wall; 85% said that the US -- and not Mexico as Trump has promised -- would ultimately pay for it. Trump's disapproval rating is hovering right around 60% -- at or near record highs for this time in a president's term.

Add those three factors up -- and sprinkle in the historic trends of major losses in the president's party in his first midterm election -- and you have a boiling cauldron of bad for Republicans.

Which is why Senate Majority Leader Mitch McConnell and House Speaker Paul Ryan have gone WAY out of their way in recent days to assure everyone that the government won't shut down next month when Congress returns to Washington.

"I don't think a government shutdown is necessary, and I don't think most people want to see a government shutdown, ourselves included," Ryan said on Wednesday in Oregon.

And/but: Trump seems to be spoiling for a fight with Republicans in Congress and appears to have settled on playing a game of chicken with Ryan and McConnell on shutting down the government if money for his border wall isn't provided.

"Believe me, if we have to close down our government, we're building that wall," Trump promised a cheering Arizona crowd during a wild campaign rally on Tuesday night.

Then, on Thursday morning, Trump went after McConnell and Ryan via Twitter.

"I requested that Mitch M & Paul R tie the Debt Ceiling legislation into the popular V.A. Bill (which just passed) for easy approval," he tweeted. "They didn't do it so now we have a big deal with Dems holding them up (as usual) on Debt Ceiling approval. Could have been so easy-now a mess!"

Then, minutes later, this: "The only problem I have with Mitch McConnell is that, after hearing Repeal & Replace for 7 years, he failed!That should NEVER have happened!"

Those Trump tweets come less than two weeks after he repeatedly attacked McConnell on the failure to pass health care reform and suggested the Kentucky Republican might need to consider stepping down as leader. And, it comes just days removed from a series of stories detailing the fact that the two men haven't spoken in weeks and have no plans to do so.

A bit more context: Government shutdowns, historically speaking, are almost always a very bad thing for the side that gets the blame.

The shutdowns of late 1995 and early 1996 -- which then-Speaker Newt Gingrich forced under the belief it would hurt President Bill Clinton mortally in advance of his re-election bid -- turned into an unmitigated disaster for the GOP. The shutdown was the beginning of Clinton's political comeback, and he coasted to victory in November 1996. Two years later, Gingrich and Republicans suffered major losses in the House -- and Gingrich quit.

The 2013 government shutdown -- which lasted 16 days and was triggered by Republican Sen. Ted Cruz's demands over defunding Obamacare -- looked to, again, be a huge problem for congressional Republicans. Their poll numbers dipped badly during the closures and the shutdown's immediate aftermath.

But the mishaps of healthcare.gov -- a slow-motion collapse that began in October and continued well into 2014 -- turned into a godsend for Republicans. It reminded their voters of who was still in charge in Washington (President Barack Obama, a Democrat) and made the country, largely, forget about how Republican majorities in the House and Senate were responsible for the shutdown.

There's one crucial difference between 2013 and today, however: Republicans control the executive and legislative branches of government. There is no Obama or Obamacare to scapegoat. There is no botched rollout of a website to villainize. Just Trump, Ryan and McConnell. And no repeal and replace of Obamacare (or much else, legislatively speaking).

And so, we have two totally contradictory lines of thinking: 1) McConnell/Ryan dead set on avoiding a shutdown, knowing the damage it could do to the near-term and long-term political prospects of their party and 2) Trump desperate for a fight to show his outsidery-ness and distance himself from GOP leaders who don't listen to him.

The problem is obvious. If Trump goes hard on his demand for border wall funding -- White House types insist he is very serious about doing so, but he is also incredibly mercurial and changeable -- he would likely have the House Freedom Caucus and a decent-sized chunk of conservative senators on his side. Which would mean that Ryan and McConnell would have to pass a government funding bill with lots of Democratic votes. And that Trump could veto whatever they passed and -- wait for it -- that they almost certainly wouldn't have the votes to overturn that veto.

If you're saying to yourself, "Trump would never do that to his own party," stop and look back at the last two years. And if you are a Republican, get ready -- because the next month is going to be a very bumpy ride.