On Thursday, the House January 6 committee voted unanimously to issue a subpoena to Donald Trump. He has indicated he is considering testifying but surely the likelihood of him doing so under oath is nil. He lacks all incentive to appear. The committee’s long-term existence is doubtful.

In their joint account of Trump’s two impeachments, Rachael Bade of Politico and Karoun Demirjian of the Washington Post suggest the US is exhausted by the pandemic and perpetual investigation. The quest for “Capitol riot accountability became an afterthought to … other crises”, they write.

Trump lost to Joe Biden by more than 7m votes nationally but only by the thinnest of margins in the battleground states. Trump is on the ballot this November, even if his name does not appear. The Republicans are primed to take the House and possibly the Senate.

In other words, Trump’s future rests with the courts and the electorate, not Congress. For all the committee’s efforts, Trump remains either hero or villain depending on demographics, habits and preferences. Political identification is an extension of self.

Against this dystopian backdrop, Bade and Demirjian deliver a granular examination of both Trump impeachments and the work of the January 6 committee. Their joint effort is a stinging indictment of what they see as Republican cravenness and Democratic ineptitude.

The former allowed Trump to evade consequences, the latter failed to master the levers of power. The authors are alarmed but their words are measured. They worry about what might be next.

“Even if they did not intend to, the Democrats’ efforts to oust Trump created a paradigm for hostile presidents to ignore subpoenas and buck [Capitol] Hill oversight,” Bade and Demirjian write.

They also posit that “a party with congressional supermajorities may one day oust a president with no evidence at all”. Said differently, the impeachment process will become wholly debased, a cudgel to be deployed as the US careens through its cold civil war. House Republicans have raised the possibility of a Biden impeachment already.

As is to be expected, Unchecked is well-sourced and noted. The book records the give-and-take between congressional leaders and members, at the same time helping the reader understand how the US reached this point.

During the first impeachment, the authors capture Mitch McConnell as he rallies his Republican Senate troops. His pitch centers on power. He depicts impeachment over Ukraine as a smokescreen for the Democrats’ ambition to take the chamber.

“This is not about this president,” McConnell said. “It’s not about anything he’s been accused of doing,” Rather, “it has always been about 3 November 2020. It’s about flipping the Senate.”

McConnell loathed Trump but understood their fates could not be separated. If McConnell were pitted against Trump in a Republican popularity contest, the Kentuckian would be squashed. He lacked Trump’s appeal and was overtly linked to the donor base. Banker’s shirts do not signal “man of the people”. For McConnell, populism was an acquired taste, if that. He could fake it, to a point. But in the Senate, he held sway.

At the same time, there was the reality of Trump’s approaches to Ukraine. As much as Trump lawyers argued there was no quid pro quo, in private, Senate Republicans weren’t buying it.

Before the first impeachment trial, Ted Cruz of Texas met Trump’s team. He argued it was irrelevant whether their client engaged in a quid pro quo. Rather, the issue was one of intent. If uprooting foreign corruption motivated the contemplated transaction, that would be legally permissible. Cruz failed to persuade the White House counsel, Pat Cipollone. As the action shifted to the Senate, Trump’s lawyers angered Republican jurors.

Alan Dershowitz equated presidential power to that of a king unchecked by parliament. “If the president does something which he believes will help get him elected, in the public interest”, that would be fine.

Roy Blunt of Missouri, a member of Republican leadership, was not amused. He demanded that Dershowitz be fired. The next day, the Harvard professor was gone.

As for the Democrats, they failed to internalize that their audience was the Republican Senate. With Trump in the White House, Adam Schiff enjoyed a meteoric rise among Democratic House colleagues. But he left Senate Republicans unmoved. In the end, they were yawning.

Fast forward to the second impeachment. Here, Bade and Demirjian depict Kevin McCarthy in all his oleaginous glory. The House minority leader devolves from someone who confronted Trump to an out-and-out sycophant.

On January 6, McCarthy lambasted Trump over the riot. Within weeks, the man who would replace Nancy Pelosi as speaker traveled to Mar-a-Lago with hat in hand. He too realized that it was Trump’s party now.

At its core, removing a president is about politics. For impeachment to succeed, it must transcend raw partisanship, a reality Pelosi expressed early on. Richard Nixon resigned because congressional allies would no longer protect him. The Watergate tapes were the smoking gun.

Now, with or without a criminal referral by the January 6 committee, justice department investigations of Trump are in full swing. On Friday, the Washington Post reported that a federal judge ordered Mike Pence to testify before a grand jury, and that earlier in the week the US Court of Appeals refused to block Marc Short, Pence’s chief of staff, from doing the same.

But that is not the end of the story. Inflation continues, interest rates on home mortgages have shot above 7%, and Biden’s relationship to basic facts appears situational at best.

With cost-of-living outstripping take-home pay, the saliency of abortion and the supreme court Dobbs decision diminishes. The Democrats also appear out of step on crime. In the midterms, shouting that democracy and the constitution hang in the balance will not be enough. Culture will always matter. Whether the Democrats can figure this out remains to be seen.

• Unchecked: The Untold Story Behind Congress’s Botched Impeachments of Donald Trump is published in the US by HarperCollins