It may be unadvisable for them personally, but it's a good thing when they do it. Trump's run for president is drawing all the demonicrat and GOPe wackos out of the woodwork, and exposing them for the wackos that they are.
What I find amusing about the attacks on Trump are
that they usually fall in line with
“he doesn’t support/believe XYZ” and XYZ is something that the majority of us despise about the status quo politicians.
So, in essence, their attacks are protesting the very reasons he has such appeal, and magnifying it.