A test for the Democratic party

What will they do if Joe Lieberman leaves the party to run as an Independent rather than lose the primary to Ned Lamont? They'd better consider that possibility seriously, as the polls are showing this race closer and closer, and the progressive base (is that what we are?) is unwilling to sit calmly if the establishment shows that incumbency is more important to them than party loyalty (see also here) -- surely if Lieberman's continual disloyalty while in office isn't enough, his actually leaving the party should have some consequences. Else, why should common folk put any meaning in party designations at all? Walk carefully on this one, gents...