A piece of the iceberg which is largely hidden broke off this week and floated to the surface of public consciousness. Donald Trump Jr acknowledged receiving an email stating that the Russian government was prepared to offer “very high-level and sensitive information” as “part of Russia and its government’s support for Mr Trump” that would incriminate Hillary Clinton. Trump Jr arranged to receive the information at a meeting attended by himself, his brother-in-law Jared Kushner and his father’s campaign manager, Paul Manafort that, in the event, proved disappointing.

As former Director of National Intelligence James Clapper said this week: “I can’t believe this one exchange represents all there is … We are headed for a constitutional crisis.” Where would be the endgame of such a crisis?

One possibility is impeachment. Although most attention has been focused on the President’s culpability for having obstructed justice by attempting to thwart the FBI investigation into the Russian connection, a more promising possibility is impeachment for bribery. Most people think of the “bribery” listed in the constitution as a basis for impeachment as the taking of a bribe, and this is certainly true. But equally important is offering a bribe. By determining that the head of the FBI, James Comey, wished to continue in his post, the President came perilously close to violating the constitution when he then stated that he would “think about it”, and raised the subject of Comey terminating the Russia investigation. Indeed, the offering of such a bribe formed one of the counts in Richard Nixon’s impeachment when it was alleged he offered a judicial promotion to a judge for favourable treatment in court.

A second possibility is indictment for the violation of a criminal statute —such as the Espionage Act, lying to a federal officer, the suborning of perjury or the obstruction of justice. But since a sitting President cannot be indicted, and can only be prosecuted once he has been removed from office — or ended his term — this is for the time being unlikely.

The likeliest possibility is the President’s resignation, as a consequence of the criminal prosecution of his children. Whatever his policy goals, it has long been clear that creating a dynasty — having destroyed the two reigning political dynasties in the last campaign — is his greatest objective. Resignation, as remote as it seems right now, might well be a choice the President would make to save his children from prison, and himself from future prosecution.

Would the President pardon them? If he did, it would seal his impeachment and his own prosecution.

Philip Bobbitt is professor of law at Columbia University