1) The Senate could entertain a motion by the president’s counsel to dismiss ‐ before the start of a trial ‐ both articles of impeachment, for failure to meet the constitutional threshold for stating a cause of action. Such a decision would require a simple majority of 51 votes because this would be a procedural motion;2) The Senate could begin a trial and, thereafter, could end it whenever the Senate majority deems it has heard enough and calls for a vote. Such a vote would be called when the Senate majority is confident that a supermajority of 67 senators ‐ two-thirds of the Senate ‐ would not vote to convict;
3) The Senate could conduct a full-blown trial, and it could drag on for as long as the Senate majority feels doing so is in its interests. It has a wide berth for calling or subpoenaing witnesses as it feels is germane. This would cause a circus-like atmosphere that would require the Supreme Court’s chief justice, the presiding officer in a Senate trial, to make numerous rulings, some of which would be unpredictable in their outcomes.
4) The Senate, after the conclusion of a trial, could once again entertain a motion to dismiss, alleging that House Democrats had failed to prove their case. This is a procedural motion that would require a simple majority to make deliberations by the full Senate moot if passed.
5) And then there is a "nuclear option." The Senate majority could make a procedural motion to adjourn the start of a trial until Nov. 4, 2020. That would allow the American people to decide the president’s fate at the ballot box. The Constitution is silent as to when a trial should occur, timewise. A simple majority of 51 votes would be necessary to pass such a motion.
No matter how the Senate deals with its "trial" obligations, the outcome does not change. The president either will be cleared by the impeachment articles being dismissed without the necessity of a trial or acquitted after a trial.
In my opinion, a trial is unnecessary. The House articles, on their face, are defective. Both fail to meet the constitutional threshold of "high crimes and misdemeanors." This would negate a trial but does not give the president any formal "acquittal," after a trial on the merits of the articles, which would prove the president’s innocence. While this would be true in a traditional criminal judicial proceeding, it is not the case in a political trial. No matter how the Senate deals with the articles of impeachment, Democrats and Republicans will put their own political spin on the outcome. Since the House articles of impeachment were voted strictly on party lines, and the country is so divided on the whole impeachment process, in my opinion, a trial is less important.