Donald Trump is assuming the presidency without a mandate from the people—and this fact drives him crazy. For the tens of millions of Americans preparing to oppose his administration and its draconian policies, this is not merely a salient detail; it’s an essential tool of resistance.

From the beginning of his presidential quest, Trump has sought to project strength. He has refused to apologize, compromise, respect a free and questioning press, or heed the advice of ethics watchdogs. This ego-driven inflexibility is a constant of Trumpism. Yet Trump is not strong. He and his aides recognize this fact, fear this fact, and push back against it with a desperation that illustrates their vulnerability.

When Trump isn’t tweeting about Alec Baldwin’s devastating portrayals of him on Saturday Night Live or ripping Meryl Streep for daring to dissent, he keeps claiming that he won the 2016 election “easily” and that the results verify the existence of a great “movement” in support of his presidency. This is false.

Fifty-four percent of Americans who cast a ballot in 2016 backed someone other than Trump. He trailed Hillary Clinton by almost 3 million votes—an unprecedented figure in the history of presidential elections. Trump only prevailed because of an Electoral College that was established more than two centuries ago as a vehicle to thwart rather than confirm the will of the people. Many of his electoral votes came from states in which the persistent assaults by the GOP on voting rights cast a cloud over the results. And Trump’s congressional collaborators have no more of a mandate than their leader. Republicans lost seats in the Senate and House in 2016, as majorities of voters nationwide opted for alternatives to the congressional candidates running on Trump’s ticket.

These are the facts that Trump and his allies seek to deny, responding angrily whenever their claim to absolute power is challenged. When Congressman John Lewis announced that he wouldn’t attend Trump’s inauguration ceremonies because he doesn’t see “this president-elect as a legitimate president,” Trump went ballistic. He attacked Lewis so personally, so viciously, so absurdly—tweeting that the civil-rights icon is “all talk talk talk-no action or results” and wrongly claiming that his district is “in horrible shape and falling apart”—that more than 25 percent of Democratic House members joined Lewis in his planned boycott.

This was not an isolated incident. Trump and his surrogates constantly claim a “landslide” victory that never happened and tear into critics who note that this emperor has no clothes. There is an ugly, authoritarian tenor to Trump’s obsession with mandates and legitimacy. His overreactions are unsettling, even frightening. But those who resist Trump must recognize that he goes to these extremes because he is the frightened one. He and his mandarins know that it will be harder to hold an unstable Republican coalition together and reach out to wayward congressional Democrats if these politicians recognize that Trump isn’t acting on behalf of the American majority. Polls showing historic levels of disapproval for Trump’s transition efforts are important, but nothing so destabilizes this desperate pretender as the reminder that by the most basic measures of democracy, he’s a loser.

This fact will be abundantly clear the day after Trump’s boycotted inauguration, when hundreds of thousands are expected to attend the Women’s March on Washington. Those protesters, joined by marchers in cities across the country, will be saying loud and clear that Trump has no mandate to privatize Medicare and Medicaid, no mandate to ramp up attacks on voting and labor rights, no mandate to deny climate change, and no mandate to make the world a more dangerous place. Those are the facts—and if they’re stated loudly enough, they will be Donald Trump’s undoing.