Parties don't descend into vicious civil wars when things are going well for them. So the fact that it's happening now to the GOP tells you a lot about what Republicans are facing, even though they control the White House, Congress, and a majority of state houses and governorships. They are beginning to tear themselves apart over the question of who is to blame for their current difficulties, with one side saying it's the fault of a feckless establishment that is insufficiently loyal to President Trump, and the other side saying — mostly sotto voce, but occasionally out loud — that the responsibility lies with Trump himself.

If the president was right in his repeated insistence that his administration has been a smashing success, there wouldn't be anything to fight about. But in truth, things could hardly be worse: No major legislation has been passed, the effort to repeal the Affordable Care Act was a spectacular failure, Trump's approval ratings are abysmal and a majority of Americans say he's not fit to be president, one Republican officeholder after another is choosing not to run for re-election, polls show Democrats headed for a dramatic win in 2018, and even the one goal Republicans were all supposed to agree on — a big tax cut for the wealthy and corporations — looks like it might be in trouble.

All of which leads to dissension from within, as White House staff rush to tell reporters that the president is an infantile rage-monster whom they have to trick into not burning down the world. When Sen. Bob Corker (R-Tenn.) expressed his concerns about Trump's erratic behavior, none of his colleagues came out to contradict him and say that in fact Trump is a wise and careful leader who is performing his duties successfully, no doubt because Corker was only saying publicly what the rest of them say privately.

But to some on the right, this all smacks of a slow-motion coup by quisling Republicans who lack the courage to stand behind Trump and testify to his greatness. Which is one of the reasons that this week, the hardline conservative group FreedomWorks wrote a letter to Senate Majority Leader Mitch McConnell demanding that he and his leadership team resign for their failure to produce a sufficient quantity of conservative legislation. While the signatories were a little on the has-been side (few are dying to hear what Brent Bozell and Ken Cuccinelli have to say these days), it was evidence of a disgruntlement in conservative circles.

Or consider Stephen Bannon, who left the White House and declared that he'd be supporting the Trump agenda (whatever that is) from the outside — which he has decided means condemning Republicans. "We are declaring war on the Republican establishment that does not back the agenda that Donald Trump ran on," Bannon recently told Sean Hannity, adding that "there's a coalition coming together that's gonna challenge every Republican [Senate] incumbent except for Ted Cruz."

Both parts of that plan raise questions about what kind of crusade this is. First, among the Republicans up for re-election are many who have been completely loyal to Trump, and second, why exempt Ted Cruz from the target list? The only logical explanation is that Cruz is a favorite of hedge fund billionaire Robert Mercer and his daughter Rebekah, who are Bannon's patrons and the ones likely to fund this effort.

Bannon's obvious goal is to burn the Republican Party to the ground in the hope that something glorious rises from the ashes. It's hard to know how successful he'll be, although the candidate he backed in the Alabama special election, religious extremist Roy Moore, beat Luther Strange, the candidate Trump himself endorsed (Bannon managed to argue that Moore would be a more faithful vehicle for Trumpism, but I wouldn't bet on it). One of the things the election showed was that conservative Republican voters won't always take their cues from Trump himself, even if they still support him.

Now imagine if Republicans were to fail in what is always their central policy goal: cutting taxes for the wealthy and corporations. It could happen, particularly if Trump barrels clumsily through the process the way he did with health care. Bloomberg News reported this week that while the White House had been saying for some time they wanted to eliminate the deduction for state and local taxes, Trump "grew angry when he learned that the change would hurt some middle-income taxpayers." In other words — and this should surprise no one — he has little idea what's in his own tax plan.

There's no reason to think that as things move along Trump will be any more up on the details, which means he'll be a force of chaos and uncertainty. And the fact that the White House has come up with a plan that would increase taxes for many people could wind up giving some members of Congress pause.

Add in the feuds Trump has cultivated with members of his own party in the Senate — where Republicans can only afford to lose two votes — and tax reform going down in flames is a genuine possibility. Should that happen, the conflicts within the GOP will get even uglier.