Senate faces unprecedented challenge of putting a former president on trial
Impeaching hearing could begin as early as 1pm on Wednesday January 20 under Senate rules which say it overtakes all other business
No former president has ever gone on trial and the rules of who will preside are unclear
A sitting president’s impeachment trial is overseen by the Chief Justice – as happened a year ago when John Roberts presided
But other options include Vice President-elect Kamala Harris because her constitutional role is to preside over the Senate
That option is unlikely given that Democrats will set the trial rules and they are likely to ask Roberts; they could also use president pro tempore Patrick Leahy
Even timing remains unclear: if Nancy Pelosi sends article immediately trial could begin an hour after Biden is sworn in
