Bob Bauer notes that Senate Republicans have the power to ignore a House impeachment of the president. The Constitution allows the Senate not to hold a trial after a House impeachment, and a Senate majority can change the current rules that provide for a trial. So it is possible, Bauer writes,
that, in this time of disregard and erosion of established institutional practices and norms, the current leadership of the Senate could choose to abrogate them once more. The same Mitch McConnell who blocked the Senate’s exercise of its authority to advise and consent to the Supreme Court nomination of Merrick Garland, could attempt to prevent the trial of a House impeachment of Donald Trump. And he would not have to look far to find the constitutional arguments and the flexibility to revise Senate rules and procedures to accomplish this purpose.
But it’s not as though impeachments of presidents are so frequent that “established institutional practices and norms” governing them can really be said to exist in the first place so that they can be eroded or disregarded.
It seems to me that the moral obligation of the Senate to try a president after a House impeachment depends entirely on the strength of the case for impeachment. If the House has made a case so strong that only the most determined partisan ally of the president can dismiss it, then the Senate should take it up and deserves to be condemned if it fails to take it up. If the House makes a weak case that only partisan opponents of the president can take seriously, then the Senate has no obligation to move forward.
And if the case is such that reasonable people can disagree, then whether the Senate should take it up will be an arguable proposition, with the debate over the propriety of its decision to hold a trial or not largely replicating the debate over the charges against the president. Judgment calls are inescapable here, and no appeal to imagined “norms” can obviate the need for them.