Former national security adviser John Bolton has said he will testify before the Senate if he is subpoenaed during the impeachment trial. This revelation has already given the Democratic Party even more of an incentive to delay passing the House’s articles of impeachment to the Senate, and it will undoubtedly put more pressure on uncertain, moderate Senate Republicans who have been trying to avoid the spotlight.

Republican leadership wants a fast impeachment trial. This makes sense: The sooner the trial begins, the sooner it will result in an acquittal. But there are at least three Republican senators who have expressed concern with Senate Majority Leader Mitch McConnell’s attempts to rush the process, and Bolton’s willingness to testify could convince them to side with the Democrats and call on McConnell to allow witnesses during the trial.