President Donald Trump’s campaign to politically punish Republicans who stand in his way moves through Indiana on Tuesday night, when seven state senators face Trump-backed primary challengers. In neighboring Ohio, primaries for U.S. Senate and governor will lock in the candidates for two major races with national implications. And in Michigan, voters in a bellwether district will fill a vacancy in the state Senate, a race with implications for the balance of power in a battleground state. Here's some key things to watch in the three states.