President Donald Trump is not on the ballot, but he has invested time and energy in a slate of primary contests across America that will again test his clout within his own party.
Voters are weighing in on candidates in seven states.
None is more important to Trump than South Carolina, where the president himself appeared at a rally on Monday night to help Gov. Henry McMaster. The Republican governor, one of Trump's first high-profile supporters, is fighting for his political life against a self-made millionaire.
South Carolina's race leads a batch of primary contests in New York, Utah, Colorado, Oklahoma, Maryland and Mississippi. With the general election nearly four months away, more than half of all states will have selected their November candidates after Tuesday.
