Voters in Virginia, New Jersey, New York and California will soon offer the strongest and earliest clues about America’s political landscape heading into next year’s consequential midterm elections.

The so-called off-year contests are part referendum, part barometer, part guidepost and possibly part springboard. Republicans will look for clues on how Americans grade President Donald Trump and their party’s governance — as well as what the future may hold when he’s no longer on the ballot.