Lots of people from the opposing party cross over in primaries when there is an incumbent running from their side.

There is always the concern over crossover sabotage, but that can sometimes backfire.

In 2010, the primary for Michigan Governor had only one viable D candidate and a whole field of R candidates. There appeared to be a lot of crossover from Dems into the R primary.

A surprise candidate, Rick Snyder, with no previous government experience won over several better known R politicians. I believe
that it was Democratic voters that assumed that a "no name" just had to be better than the others that allowed him to win the primary. Unfortunately he won easily in the General Election and enacted many damaging policies during his two terms.

Not so sure that wasnt one of the factors that led to Trump getting the nomination in 2016.

Quote in today's Detroit Free Press by a prominent progressive activist.

"Mark Grebner, a Democrat and founder of Practical Political Consulting in East Lansing, crossed over and voted for Trump in 2016 thinking he’d never win the nomination or the general election and would fare the worst against Democrat Hillary Clinton."