Off-year elections usually are about voter intensity. In dozens of contests over the past year, since Trump was elected, the energy has been with Democrats. Most recently, a Democrat won by seven points in a pro-Trump, pro-Republican state legislative district in Sarasota, Florida, in a special election.

The hope for the dozens of embattled congressional Republicans is that by November their base will get energized. Those voters remain strongly supportive of Trump, while the general electorate, despite some recent improvement in the president’s standing, is far less so.

If Republican candidates in blue districts and states run away from Trump, some of the GOP base will stay home; if they wrap themselves around him, they risk energizing Democrats and alienating independents. It’s not an easy choice.