Two legal blows for close associates of President Donald Trump highlight the acute difficulties he faces from criminal investigations ahead of November’s midterm elections. His former personal lawyer and fixer Michael Cohen said Trump directed him to make illegal payments to silence two women who say they had sexual affairs with the president. Trump’s 2016 campaign manager Paul Manafort was found guilty of tax and bank fraud. Both men face further investigations that may link them even more closely to federal crimes, just as special counsel Robert Mueller’s inquiry concludes its report on whether Trump colluded with Russian agents in the 2016 presidential election.

These are serious problems for the president in the most troublesome political period of his presidency so far. The United States is above all a law-governed polity in which legal process mediates democratic accountability. The US presidency’s strong executive authority and permissive national election funding rules are constrained by law as well as politics. With law comes strict penalties for people found guilty, making plea bargaining attractive for those accused. The same applies to legal jeopardy, where the president might be charged with a crime, and to impeachment, where the US Congress would find him politically culpable.

Trump is drawn closer to such possible outcomes by the Cohen and Manafort cases. Cohen has now sworn he paid off the two women concerned “in coordination with and at the direction of a candidate for federal office”, thereby implicating Trump in a federal crime relating to campaign financing. Manafort faces future charges of money-laundering and acting as a foreign agent in his dealings with Ukrainian and Russian oligarchs. Trump says there is no evidence that he colluded with Russia during the election campaign; but plea bargaining by the two men and extensive evidence given to Mueller by the White House lawyer Don McGahn make him acutely vulnerable to criminal charges when the counsel’s report is issued.

Whether the president is capable or liable to be criminally prosecuted is disputed in Washington by legal, constitutional and political experts. Theoretically that might be possible but it has never happened. Impeachment is the more likely pathway, putting politics ahead of the law. That makes November’s elections all the more salient if the Democrats win control of both the House and Senate. Congressional Republican loyalty to Trump is stretched to breaking point if members risk losing office over his credibility.

Experts also debate whether the president might pardon Cohen and Manafort - or even himself. Trump says the whole process is a “witchhunt and a disgrace” and a media fake news campaign directed against him personally, having nothing to do with Russian collusion in the 2016 election. A presidential pardon risks passing that judgment on to the electorate. Trump’s bulletproof record is undoubtedly facing its greatest test.