Ron Klain, a Post contributing columnist, served as a senior White House aide to Presidents Barack Obama and Bill Clinton and was a senior adviser to Hillary Clinton’s 2016 campaign.

Last October, we were in the midst of debate preparation for Hillary Clinton when news of the “Access Hollywood” tape broke. The senior Clinton team immediately wondered what the event’s impact would be. Would there still be a debate two days later? Would Donald Trump show up? Would his running mate, Mike Pence, take his place? How could Trump survive?

Trump not only showed up for the St. Louis debate that Sunday, he stood on the stage and told Clinton that if it were up to him she’d “be in jail.” Ten days later, Trump insisted at the Las Vegas debate that allegations made against him by nine women of groping and other unwelcome physical contact were so baseless that he “didn’t even apologize to [his] wife” for his actions. Twenty days after that, Trump was elected president of the United States.

The lesson: It is dangerous to underestimate Trump’s survival skills. And so, as the appointment of a special counsel to investigate the Russia mess has Washington buzzing with nascent impeachment talk, 25th Amendment scenarios and rumors about resignation, it is worth remembering how tenaciously Trump pursued power, along with five key assets he has to maintain his grip on it.

First, while he is proving to be an incompetent president, Trump is an incredibly skilled politician. He did not come to the presidency by accident: He spent 30 years laying the groundwork for his run — attacking President Ronald Reagan on trade in the 1980s, putting out a campaign book in 2000, forcing President Barack Obama to release his birth certificate in 2011. He vanquished an all-star GOP field in 2016 — beating a Bush, the Republicans’ Obama (Marco Rubio) and lionized candidates such as Scott Walker and Chris Christie. He resoundingly won the Republican primary in New Hampshire. He was the host of a top-rated television show for almost a decade: no small communications achievement.

Second, there is the power of the presidency, and Trump’s ability to use its allure as a bulwark against accountability. Trump’s staff may feud with one another, but — with two family members ensconced in the West Wing — they seem prepared to defend him by any means necessary. Well-regarded people — such as national security adviser H.R. McMaster and Deputy Attorney General Rod J. Rosenstein — have shown a willingness to sacrifice their own credibility to protect Trump. And a retinue of prominent law firms appear ready to provide legal and public relations cover in defense of Trump and his family.

Third, there is the desire of many observers to try to normalize Trump and get “back to business.” This obviously includes most Republican members of Congress, who have shown a penchant for dismissing concerns about Trump so long as he continues to pursue an agenda of repealing Obamacare and cutting taxes.

But this instinct extends beyond partisans: Remember how media commentators, including some liberal voices, acclaimed Trump’s presidential leadership after one well-executed speech three months ago? It might take shockingly little — a successful foreign trip next week or progress on Obamacare repeal in Congress — for pundits to conclude that he is “back on track.”

Fourth, there is the intensity of his most devout supporters. While Trump has falsely boasted about many things, he was probably right when he said that he “could stand in the middle of Fifth Avenue and shoot somebody” and still maintain their support. Trump’s “tribal” supporters back him, not because of what Trump does or says, but because they want the affiliation they enjoy as Trump supporters. While these hard-core supporters were not sufficient to put Trump in office — experts believe this group is 25 percent to 40 percent of the electorate — even at the lower end of that range, they make up a majority of Republican primary voters in most Republican-held districts. That is a powerful check on Republican senators and representatives who might stand up to Trump — as House Speaker Paul D. Ryan (R-Wis.) learned when he was booed in his own district for distancing himself from Trump during the “Access Hollywood” conflagration.

And fifth, there is the frightening risk that Trump’s die-hard supporters are more devoted to Trump than they are to the rule of law. The United States prides itself on being “a government of laws, not of men,” but polls show that an increasing number of Americans generally, and Trump supporters specifically, have “lost faith in democracy.” Sinclair Lewis’s brilliant novel “It Can’t Happen Here” portrayed an alliance between populist rhetoric and corporatist policies that established an iron grip on government and trampled legal accountability. A Trump campaign email, sent the day the latest Comey allegations emerged, echoed Lewis’s depiction, labelling the growing scrutiny of Trump as “sabotage,” accusing government officials of being against an “America First agenda” and urging supporters to “be prepared to go into the trenches to FIGHT.”

Trump is down but not out. Indeed, he may even be at his most dangerous in “wounded animal” mode. The effort to hold him accountable for any abuses of power will face formidable obstacles in the weeks and months ahead. He should not be underestimated.