[Ed. – Interesting assessment from Dershowitz. If the Senate did this, is there anything the House could do about it, other than try to obstruct general federal business as a retaliatory move?]
I believe that the Senate need not wait for articles of impeachment to be transmitted. Senators are empowered by the constitution to begin a trial now— with or without further action by the House.
Just as the House has the “sole power of impeachment,” so too the Senate has the “sole power to try all impeachments.” The Senate can make its own rules (as long as they are consistent with the constitution) and establish its own timetables.
The only possible rejoinder to this constitutional verity is the argument put forward by [Noah] Feldman that the House has not yet concluded the process of impeachment, and so the Senate has no jurisdiction to proceed to trial. What follows from that argument is the conclusion — utterly unacceptable to [Laurence] Tribe — that President Trump has not been impeached and if the articles are never transmitted he will not go down in history as the third president to be impeached, because the House never completed the necessary process by sending the articles to the senate.