In the past few weeks, the impeachment of Donald Trump has moved from the realm of liberal fantasy to real, if still distant possibility. The U.S. president violates democratic norms and expectations around presidential conduct. And with each fresh outrage, the American system’s ultimate political sanction becomes more thinkable.

If and when the House Judiciary Committee takes up the question of impeachment, it will have a running start. Legal scholars, including Laurence Tribe, of Harvard have begun work on sample articles in the indictment.

As during Watergate, there is broad agreement that the first article would be the obstruction of justice. By his admission, Trump fired James Comey as director of the FBI because of the probe into links between his presidential campaign and Russian interference in the 2016 election. Comey contemporaneously documented Trump’s request that he let go of the investigation into Michael Flynn, the president’s former national security adviser. Comey’s memos, combined with Trump’s admission, make a strong prima facie case.

A second article of impeachment might revolve around accusations of conflict of interest and corruption. Trump, who has neither released his tax returns nor properly separated himself from his real estate, hotel, and golf businesses, stands to profit enormously from his time in office. Doubling the membership admission fee at his Mar-a-Lago resort (to $200,000) is a crude and obvious way of selling access while in office. The elevated rates paid by visiting diplomats at his new Trump International Hotel, just blocks from the White House, trigger the Emoluments Clause of the Constitution, a specific prohibition against officials receiving payments from foreign governments.

A historically grounded understanding of what the American founders meant by the phrase “high crimes and misdemeanors” arguably covers a much wider range of presidential abuses. Another Harvard law professor, Noah Feldman, argues that the president’s slanderous accusation that Barack Obama tapped his phones in Trump Tower constitutes an impeachable offence, along with Trump’s bilious defamation of the press.

A president cannot be criminally prosecuted for disclosing classified information, as Trump apparently did when he bragged to Russian officials about his fantastic intelligence on ISIS. But gratuitously harming national security by spilling secrets in this way is arguably an impeachable offence too.

The specifics of possible charges are somewhat beside the point. Whether impeachment hearings take place is ultimately a political question much more than a legal one. And so long as Republicans control the House, they remain unlikely. Since Trump became the GOP nominee, people have continually wondered whether this or that catastrophe would finally cause Republican legislators to break with him. Would the Access Hollywood tape, in which Trump bragged about sexual predation, be the straw that broke the camel’s back? Would his bigoted attacks on a Mexican American judge?

But the camel’s back is the wrong metaphor. Members of Congress are less beasts of accumulating burden than computational machines designed to win re-election. Their sense of their own political interests is acute. Thanks to gerrymandered congressional districts, a large majority of Republican House members hold safe seats, where the risk of losing to a Democrat is minimal. Their greater concern is a well-financed primary challenge from the right.

Only when legislators judge that the risk of continuing to support Trump outweighs the risk of abandoning him will they begin to jump ship. Their support is likely to hold firm so long as Trump’s approval rating among Republicans remains greater than 80 percent.

This political calculation should not be confused with loyalty—many Republican politicians privately feel (and express) contempt for Trump. The party’s greater loyalty is to a conservative agenda that includes tax cuts, deregulation, and the repeal of Obamacare.

If Trump comes to be seen as an obstacle rather than an avenue for that agenda, party leaders could turn on him. With scandals metastasizing and special counsel Robert Mueller at work, the prospect of a paralyzed presidency is growing.

At the same time, Republicans cannot simply decide they would be better off disposing of Trump in favor of the vice president. Were Trump to be forced from office, Mike Pence would take over in conditions akin to 1974, when the GOP faced public rejection after Watergate. The party leadership understands that there is no good scenario for the party that involves Trump leaving office before his time.

Impeachment becomes a more likely prospect if control of the House shifts in the 2018 congressional election. But even if Democratic efforts to focus the midterm on impeachment succeed, it takes a two-thirds vote in the Senate to remove a president from office. The ultimate decision about whether Trump serves out his term will remain in Republican hands.

A slightly different version of this article ran in the Financial Times.-