This essay was adapted from the book “Resistance: How Women Saved Democracy from Donald Trump” by Jennifer Rubin. Copyright 2021 by Jennifer Rubin. William Morrow/HarperCollins Publishers.

Donald Trump’s victory in 2016 came as a shock to Republican-leaning women like me who had crossed party lines to vote for Hillary Clinton.

I had always voted Republican for president — from my first vote, for Ronald Reagan, to my last, for Mitt Romney. I admired mainstream Republicans who were dedicated to victory in the Cold War. I looked to free markets for expanded economic opportunity and embraced free trade and robust legal immigration.

If I differed with “movement conservatives” on some issues, I appreciated their preference for incrementalism and resistance to allowing centralized power to bigfoot the “laboratories of democracy.” I shared their wariness that the executive branch had aggrandized power at the expense of Congress. And I held the deep conviction that character matters in leaders, that public virtue is not an oxymoron and that truth is not relative.

Given that I actually believed in these things, I watched in horror in 2016 as Republicans embraced a racist bully bent on undermining our democracy and promoting White Christians’ quest for political dominance. I witnessed one conservative “intellectual” and “respectable” publication after another deny, then rationalize, then defend and then laud a detestable figure who repudiated principles and positions that once animated them.

I saw social conservatives who demonized Bill Clinton swoon at the feet of a serial liar, adulterer and racist whose cruelty became a central feature of his presidency. Republicans who once insisted character was a critical factor in selecting leaders seemed almost giddy when Trump unleashed his personal viciousness on their progressive opponents.

Indeed, I had experienced Trump’s misogynistic wrath myself. In December 2015, I wrote a column for The Post in reaction to his taunting demand that CNN pay $5 million to charity in exchange for his appearance at a Republican presidential debate. Of Trump’s attempts at a shakedown, I wrote: “That would give Trump, who has done worse in each successive debate, an excuse to beg off. Why is he scared of debating his competitors?” I suggested that he couldn’t speak cogently on substantive issues, “especially foreign policy, where he has blundered in the past.”

This evidently struck too close to home. Trump tweeted, “Highly untalented Wash Post blogger, Jennifer Rubin, a real dummy, never writes fairly about me. Why does Wash Post have low IQ people?” This tweet instantly made me a target of his base, many of whom hurled vulgar insults by email and social media. The hate email and tweets, often threatening and antisemitic, were a preview of what was to come for me and for scores of women when MAGA’s cult of toxic masculinity implicitly encouraged its devotees to harass and threaten critics of its leader.

For months, I harbored some hope that Republicans would come to their senses and deny Trump the nomination. That fantasy faded with each primary victory. With no hesitation, I concluded I could not remain in a party that embraced a character so at odds with American (let alone conservative) values. In May 2016, I wrote a column “breaking up” with the GOP. I wrote it because I was still “a believer in America’s ability and obligation to do good in the world; in the wonders of the free market — including free trade and legal immigration; in limited but energetic government (although not all centralized at the federal level); and in the rule of law and individual rights” and I could no longer remain in a party warped by Trumpism. I took a step that permanently severed my bonds with many past allies.

Later that year, I cast my first presidential vote for a Democrat. Like most voters, I never expected Hillary Clinton would lose. The outcome left me gobsmacked and despondent. But I also did not expect that millions of women shared my sense of dread and disorientation. The 2016 election would spawn a new spirit of resistance to a party that abandoned loyalty to the country, the Constitution and the truth.

I embraced my new role as a former Republican. I marveled as previously uninvolved women from Chesterfield County, Va., to Midland, Mich., to Los Angeles to Alabama self-organized and remade American politics. Social media’s ability to foster connections accelerated the pace of their organizing — and sped up my own political recalibration.

Trump’s election had awakened women who imagined that our democracy was secure from a homegrown authoritarian and that their progress toward full equality was irreversible. In following women I otherwise might never have known or agreed with, I joined a broad alliance between Democrats and former Republicans bound together in a common effort to prevent devastating corruption of public institutions and contain Trump’s authoritarian impulses. As frustrated as I became with GOP toadyism and the mainstream media’s false equivalence between the parties, women’s activism convinced me that participatory democracy was thriving.

Over the next four years, women who had never run for elected office — Abigail Spanberger of Virginia, Amy McGrath of Kentucky, Elissa Slotkin of Michigan and Mikie Sherrill of New Jersey, to name four — grasped that politics was no longer about what other people did. I felt in sync with moderate women with national security credentials, the sort of grown-ups who a generation or two ago could have just as easily been Republicans. Other women who sought office in statewide contests and eventually the 2020 Democratic presidential primaries prompted me to root for Democrats and not merely against Republicans.

Trump’s presidency spurred mass protests against his Muslim travel ban, the inhumane child separation policy and systemic racism in policing, but it also forced me to more critically assess the GOP. Sentiments that once existed only at the party’s margins — know-nothingism, authoritarianism and white grievance — soon defined the party. The GOP’s utter contempt for governance (e.g., trying to repeal Obamacare with no viable alternative; corrupting the Justice Department; leaving hundreds of top jobs unfilled) convinced me that Republicans were unfit to hold power.

The Democrats’ sweeping gains in the 2018 midterms offered some hope that conscientious citizens could reclaim America’s best traditions — as did the emergence of four female senators running for the Democratic presidential nomination: Elizabeth Warren of Massachusetts, Kamala D. Harris of California, Amy Klobuchar of Minnesota and Kirsten Gillibrand of New York. Along with other NeverTrumpers, I implored Democrats to nominate someone electable, and I rejected the notion that Democrats had moved far left.

I would have been thrilled with a female nominee like the moderate Klobuchar, but Joe Biden’s nomination reassured disaffected Republicans looking for a center-left, decent person willing to champion respect for the rule of law, inclusion, a values-based U.S. foreign policy and clean, competent governance. He struck me as the only contender who could stitch together a winning coalition. And if Harris could survive the tag of an “ambitious woman” and still be picked for vice president, perhaps women could finally put Hillary Clinton’s 2016 defeat behind them.

When the votes were counted — many times, as it turned out — the outcome was mixed. Yes, Biden won with 306 electoral votes and with a popular-vote margin of 7 million, but Republicans made unexpected gains in the House and managed a tie in the Senate. Without the huge gender gap in Biden’s favor, Trump would have won reelection.

Roughly nine months into Biden’s term, we have not erased the scourge of Trumpism, nor has Biden’s performance been flawless. He was unprepared for the migrant surge along the southern border and failed to anticipate the immediate collapse of Afghanistan’s government. Nevertheless, as promised, Biden is a normal president who communicates in speeches and official statements (not on Twitter) and does not use the White House to enrich himself or punish enemies. More important, he understands that “America is an idea” — not the exclusive province of White Christians. In that regard, I have never been happier with my vote.

If anything, I now worry that Democrats lack the instinct for the jugular needed to expose the GOP’s seditious conduct, habitual lying and radical obstructionism. The Democrats’ naive belief that policies alone can win the day is misplaced when opponents will stop at nothing — not voter suppression, not remorseless disinformation and not race-baiting — to secure power.

Democracy’s secret weapon? Its women warriors. They know how to organize, how to transform themselves into activists and candidates, and how to speak to voters who don’t automatically vote for anyone with a “D” next to his or her name. If Democrats prevail again in 2022 and 2024, credit will likely go to millions of women who taught us not to underestimate the power of self-starters. However, if we learned anything from Jan. 6, it is that democracy remains fragile and Trumpism is not behind us.

My top priorities remain what they were nearly five years ago: the preservation of our democracy and reaffirmation of objective reality. My comprehension of the threat of white supremacists continues to deepen. And most important, my conviction that women’s political engagement is vital to the survival of our democracy remains undiminished.