Modern conservatives have honed in on the weaker points of the American government and spun it to their advantage. Our first past the post voting system inherently causes a two-party system to emerge where political and ideological polarization is inevitable. With this in mind, Republicans realized that there was no new party on the horizon set up to replace either major party. So instead of using a big tent approach and expanding the base by embracing a variety of viewpoints, conservatives on the far right of the American spectrum took the opportunity to seize power by focusing on one thing: winning elections (something conservatives have generally been better than liberals at over the past 50 years anyway).
In furtherance of this lone goal of winning elections consequences be damned, the Tea Party faction of the Republican Party laid the foundation of expediting political polarization by acting almost solely as a foil to the opposing party: 1) Obama is a Muslim and isn't a citizen; 2) repeal and replace Obamacare (no alternative provided); 3) oppose any progressive type reforms (anti-Wall Street, anti-black lives' matter, anti-voter reform, anti-any substantive policies that Democrats provide; 4) utilize right-wing media to spread this propaganda to undermine well-entrenched American institutions; 5) prey on the American electorate's fear of change (immigrants, non-Christians, anybody who isn't well-off or white); 6) anything we don't agree with is "fake news."
These steps worked to hasten polarization and paved the way for Donald to become president in an era where everything is made up and the facts don't matter. Republicans exposed our government's weak points (i.e. how weak checks and balances actually are, continued to expand the powers of the presidency vis-a-vis the legislature, point out that nothing can really happen if Congress simply acquiesces to the executive's demands) and used this to seize power while putting our institutions in real danger.
The way back for Democrats is unclear at this point. They continue to operate in good faith while Republicans rightfully note the paradigm shift that right-wing conservatives created. Where do we go from here? Unclear to me, but Democrats have to acknowledge that Republicans have crossed the Rubicon as far as American politics post-FDR are concerned and that the game is completely different. Until they do, they're going to continue to struggle against the united Republican front that just has one goal: win elections by being the party of anti-Democrats. They win elections without policies, without a coherent goal, and without any care for the damage they cause because they rejected nuance in favor of "own the liberals." And with the aid of the Electoral College it's working and I think will continue to work.
TLDR: Conservatives changed the rules of the game and undermined American institutions to win elections and it worked. Is there a way back from a scenario where facts you don't like become "fake news?" It remains to be seen but Democrats need to acknowledge the game has changed to win.
