As a lifelong Democrat and the son and grandson of Democrats, I would vote ordinarily in the Democratic primary for the candidate I thought closest to me politically. And I think it’s almost always a terrible idea to vote in the opposing party’s primary for a “weak” candidate you think your candidate can beat.
But in 2018, if the opportunity presents itself, I stand ready to vote in the Republican primary to boost the fortunes of any moderate candidates who come out squarely against the inevitable Trump-Bannon candidates. And I would encourage any Republicans to vote in the Democratic primary for candidates who can attract the votes of moderate Republicans and independents against these Trump-Bannon Republicans in the general election.
Extraordinary times call for extraordinary measures.