WASHINGTON — What is the Republican Party?

Suddenly, this has become one of the central questions of the 2016 campaign. It’s not simply a matter of whether the GOP is the party of Donald Trump or the party of Paul Ryan. It is also an issue of whether Republican congressional leaders have any connection with the seething grass roots whose anger they stoked during the Obama years but always hoped to contain. Trump is the product of their colossal miscalculations.

And then there are the ruminations of millions of quiet Republicans — local business people and doctors and lawyers and coaches and teachers. They are looking on as the political institution to which they have long been loyal is refashioned into a house of bizarre horrors so utterly distant from their sober, community-minded and, in the truest sense of the word, conservative approach to life.

This election has been transformed. Its trajectory will now be divided between Before the Video (BV) and After the Video (AV). Hillary Clinton was always likely to win, but BV, it seemed she would have to scratch out a normal, and perhaps even narrow, victory. AV, Republicans all the way down the ticket are running for their lives. Clinton has already started to divert some of her rhetorical energy to helping Democrats in Senate and House races, and Democratic money sources are moving to try to make Nov. 8 a day of victory at all levels.

Taking control of the Senate is well within the Democrats’ reach. Winning the 30 seats they need in the House is still a long shot because of partisan gerrymanders and the concentration of Democratic votes in big cities. Still, the fact that the possibility is even being discussed is a sea change, and the success of many of those gerrymanders for the GOP depended on large suburban margins. It is precisely suburban voters, Republican and independent, who are Trump’s nemesis.

And for those running on the ticket headed by Trump, there are no good options. Logic would dictate abandoning him, and that’s what the party’s candidates did in droves following the video’s release. But Trump has engendered deep loyalties among core Republican voters, and dumping him carries a price — a price that Trump was happy to raise sky high.

“Disloyal R’s are far more difficult than Crooked Hillary,” he tweeted on Tuesday. “They come at you from all sides. They don’t know how to win — I will teach them!”

His unloading on Ryan after the House speaker said he would no longer defend or campaign with Trump underscored that there is no middle ground. Ryan did not withdraw his endorsement, after all. But if you are not wholly with Trump, you are against him.

The flip side of this calculation is also bad for Republicans. Democratic polling suggests that voters see GOP politicians who backed Trump and left him only AV as opportunists — which is a fair reading of the behavior of people who should have known better. Republicans who took a principled stand against Trump from the beginning ought to fare better, but many of them may get hurt anyway because they represent districts and states where Trump will get swamped.

Trump’s fiasco, in the meantime, has eased coordination problems on the Democratic side. A top Democratic campaign official said there had been some tension earlier in the year over Clinton’s focus on casting Trump as uniquely ill-fit for the presidency. Down-ballot Democrats worried that a narrow focus on Trump’s deficiencies might not be helpful to the rest of the party.

Now, both Democratic candidates and the Clinton camp are united in calling out Republicans who have either endorsed Trump or refused to disown him. This creates pressure for vulnerable Republicans to defect, which helps Clinton, but also ties the entire Republican ticket to Trump, which helps her party’s Senate and House candidates. There is, said the Democratic official, “no lack of harmony.”

For years, Republicans managed an exceptional acrobatic act: to mobilize right-wing populist anger and white working-class voters behind a program whose benefits flowed to the economic elites. The operation was supported by large expenditures from the very rich. The assumption was always that the base would get the noise and the elites would get the policy.

Now the noise is deafening, a dangerous and profoundly flawed man leads the party, and its candidates cannot move one way or the other without falling off the wire. No one expected an implosion this spectacular.

E.J. Dionne Jr. is a columnist with The Washington Post. His email address is: ejdionne@washpost.com. Twitter: @EJDionne.