President Trump’s critics have repeatedly complained that when it comes to his rhetoric, attacks on democratic norms and incompetence, “Nothing matters.” We’ve learned in the last couple of months just how wrong that is: His approval has cratered; Democrats won the House with a 40-seat trouncing; House Speaker Nancy Pelosi (D-Calif.) continues to run rings around him; and Republicans now part with him on Russia policy matters — and a smaller number on reopening the government.

Court filings show that Paul Manafort continued to communicate with Trump’s lawyers during the time he was supposed to cooperate with the special counsel. He allegedly gave private polling information to and discussed a Ukraine peace deal with Konstantin Kilimnik (i.e., colluded) during the campaign.

Rudolph W. Giuliani seemed to acknowledge that Trump campaign staff may have colluded with Russians even if Trump did not — but then, collusion isn’t a crime (or something).

While the special counsel’s office, in an unprecedented move, called into question a BuzzFeed article concerning purported evidence of Trump’s subornation of perjury, Cohen has provided evidence that Trump continued to pursue the Moscow Trump-branded tower deal during the 2016 campaign.

Contrary to pessimistic assessments of his durability, Trump’s chances for a second term are shrinking with little hope of an about-face in public opinion. How did we get to this point?

First, special counsel Robert S. Mueller III does his job methodically, secretly and effectively, wrapping up one witness after another. Despite the Trump onslaught, he retains the confidence of most Americans. The Pew Research Center reports, “A majority (55%) remains confident that special counsel Robert Mueller is conducting a fair investigation into Russian involvement in the 2016 election. Confidence in Mueller has held steady over the course of the past year, and there remains more confidence in Mueller to conduct a fair investigation than in Trump to handle matters related to the inquiry appropriately.” By contrast, the same poll shows the public trust in Trump continues to drop. “A majority of the public (58%) says they trust what Trump says less than they trusted what previous presidents said while in office,” Pew Research Center finds. “Just 26% say they trust Trump more than previous presidents, while 14% say their level of trust in Trump’s rhetoric is about the same as for past presidents.”

The further Mueller digs, the worse the facts get. Trump’s constant lying matters only insofar as it implicates himself in a conspiracy to obstruct the investigation. What Mueller says and does matter most of all. What doesn’t matter? Anything Giuliani says.

While Senate Majority Leader Mitch McConnell (R-Ky.) still refuses to bring up legislation to protect Mueller, Republicans and Democrats alike — even his acting attorney general and his attorney general nominee — make clear Trump cannot fire Mueller without unleashing a firestorm with, most likely, serious calls for impeachment. Keeping Mueller in place arguably has been the single biggest factor in eroding Trump’s power.

Members of Congress discussed ways to break the funding impasse on Jan. 20, the 30th day of a partial government shutdown. (Patrick Martin/The Washington Post)

Second, Trump’s play-to-the-base strategy was a blunder with enormous ramifications. Sure, about 30 percent of the electorate will believe whatever Trump says, no matter how absurd. The Trump cult however now stands isolated from everyone else. A base-only strategy with a blundering, offensive president — who did virtually nothing for the “forgotten man and woman” and who alienated college-educated voters (in part with his racism and rejection of reality), women and suburban voters — put the House in Democratic hands.

The election not only transferred the power to investigate and subpoena Trump; it empowered Pelosi, the most formidable political opponent — maybe any opponent — he has ever faced. She managed to maneuver him into a grossly unpopular shutdown, continues to highlight his irresponsibility and, by denying him a stage for the State of the Union, prompted him to reveal and nix a congressional visit to Afghanistan; his White House then leaked her commercial travel plan. Never has Trump looked more peevish and less presidential. We see how one set of errors begets another, sending Trump into a political death spiral.

Third, in the midst of a scandal, most presidents can fall back on their role as commander in chief and architect of U.S. foreign policy to sustain their aura of power. Trump’s foreign policy, aside from the taint from his subservience to Russia, is characterized as chaotic, frightening and entirely ineffective. From his trade war that harms U.S. farmers, consumers and business, to his irresponsible plan to pull out from Syria, to his constant threats to NATO, to his foolish indulgence of North Korean tyrant Kim Jong Un, Trump’s foreign policy further saps his reputation an authority. If President Richard M. Nixon could rely on foreign policy achievements (e.g. China) to sustain him during the dark days of Watergate, Trump’s foreign policy increases the urgency of getting him out of office. (“Get rid of him before he does any more damage!” is a reasonable reaction to his destructive tendencies.)

Fourth, Trump’s narcissism, incompetence and rotten judgment have led him to force out any adviser with a modicum of common sense, experience and influence. There is no one to head off or help get him out of jams he gets into. There is no Jim Mattis to reassure allies and clean up Trump’s sloppy rhetoric; no Gary Cohn to fend off tariffs. Surrounded by yes-men, callow relatives and enablers, Trump’s bad days increase and achievements become scarce. Again, Trump is his own worst enemy.

Finally, a primary challenge to Trump was once unthinkable. However strongly Republicans cling to Trump in the face of Democratic attacks and harsh media coverage, Republicans are increasingly open to a primary challenge. In the latest NPR-PBS NewsHour-Marist poll, 43 percent of Republicans want a primary challenger, while only 46 percent do not. The second inauguration of the popular, anti-Trump Maryland Gov. Larry Hogan has intensified interest in him running for president. If Hogan jumps in and starts moving in the polls, others may follow.

This is not a prediction that Trump will be impeached and removed or forced to resign. Republicans remain sheeplike in their devotion. However, it is more likely than at any time in his presidency that he won’t finish or won’t be nominated. And if by some miracle he survives a primary challenge, he’ll reach the general election bruised and battered, a much easier target than any president since Gerald Ford. Indeed, with each passing day, the 2020 election looks like the post-Watergate 1976 election. Now imagine 1976 if Nixon were still the incumbent.