Graham Platner is out of Maine's Senate race. That may improve Democrats' chance of defeating Republican Susan Collins—but it doesn't guarantee it.

Now comes the hard part: replacing Platner without reinforcing the perception that party elites, not voters, are choosing the Democratic nominee. The process could matter just as much as the candidate.

In the latest episode of the GZERO Debrief, Eurasia Group US Practice Head Clayton Allen says Democrats may be better off than they were a week ago, but Republicans remain the favorites to hold the Senate seat.