President Donald Trump has so completely dominated American politics at this stage that his adopted party must sink or swim on his success. He has pulled out all stops in his mad dash of red-state campaign rallies in which he has continued to conduct his scorched-earth strategy of fear and vilification to carry the day.

In the course of doing so, he has changed the very face of the Grand Old Party into a wrecking crew of American ideals toward immigration and recently toward citizenship itself, to maintain a presidency that has fallen into chaos and political expediency for survival.

By intent or circumstance, Mr. Trump in less than two years has hollowed out the old Republican establishment born in Lincoln’s time and sustained in various reinventions under Theodore Roosevelt, Dwight Eisenhower and Ronald Reagan.

What has remained is a shell dominated by this president’s arrogance and self-absorption, and fed by his whims and compulsions to arouse fears of the unknown, the imagined or even the invented among his trusting base.

As a result, there is today no semblance of any other Republican poised or even willing to challenge or confront him on what the party has stood for in the past, what it stands for now, or what it will stand for in the future.

The one other party-establishment giant who had the gumption and political firepower to take on Mr. Trump, Arizona Sen. John McCain, has passed on, but living in memory remains his classic rebuke of the sitting president in casting the deciding vote that saved Obamacare from his ax.

Other party officials seen as remnants of the old establishment, starting with retiring House Speaker Paul Ryan, have benignly rolled over before the Trump steamroller. Even in Trump’s Department of Justice, Attorney General Jeff Sessions has settled for being a humiliated lapdog, even as career FBI agents loyally carry out their duties in Robert Mueller’s special counsel investigation into Russian election meddling.

As for Mr. Trump himself, he has focused these final campaign hours on reminding the faithful of those thousands of Latin American would-be rapists, criminals and alleged Middle East infiltrators doggedly slogging northward with their children to take American jobs, and other such diabolical conspiracies.

It has thus fallen to the Democrats in the congressional midterms to offer any meaningful opposition to the crafty New York political novice. They have decided, probably wisely, to focus on salvaging their cherished agenda of the New Deal-inspired social safety net protecting Social Security, Medicare and health insurance, including benefits for pre-existing conditions.

Late public opinion polls cautiously suggest that the Democrats may exceed the 23 House pickups they need to take control there, where more investigations into Mr. Trump and potential impeachment proceedings must originate. In the Senate, the polls indicate a tougher pull for the Dems to get the required two seats to take charge.

Political junkies and television pundits seem in for a very late Tuesday night, before many of them eventually crow that they knew all along how it all would turn out.

Jules Witcover is a syndicated columnist and former longtime writer for The Baltimore Sun. His latest book is “The American Vice Presidency: From Irrelevance to Power” (Smithsonian Books). His email is juleswitcover@comcast.net.