Until now, the scope of Special Counsel Robert Mueller’s investigation into Russia’s interference in the 2016 election was unclear. While it was obvious that some of Trump’s underlings had been entangled in the investigation, it was unknown how far it extended up the chain of command. Trump himself, citing fired FBI Director James Comey as an authority, claimed that he himself was not under investigation.

We now know this is no longer true. As the Washington Post reports, Mueller “is interviewing senior intelligence officials as part of a widening probe that now includes an examination of whether President Trump attempted to obstruct justice, officials said.” The obstruction of justice investigation apparently started after Trump fired Comey. This makes sense on two counts: 1) Comey’s firing itself could be seen as an attempt to influence the investigation; and 2) Comey’s public testimony since then strongly suggested that Trump had tried to squash the probe. The investigation is also looking at possible financial misconduct by Trump associates.

With the president under investigation, the possibility of Trump being impeached increases. If Mueller’s investigation finds evidence of wrongdoing, it will likely be presented to Congress. Republicans would then face a real dilemma: What would hurt them more, going after Trump or ignoring the evidence?