Lott is politically done, toast, finito.
Trent Lott should announce he is stepping down as the ML and say he will support who ever is chosen to lead the party and he will make every effort to help the Party of Lincoln continue to represent all of America.
I do not think by any stretch of the imagination that he should resign from the Senate. In this case, The people of Mississippi elected him and ONLY the people of Mississippi should make that decision.