What's at stake

Control of the U.S. Senate could hinge on this South Carolina seat.

The Republican nominee will face a November general election opponent and influence Senate majority math and committee composition.

Who's in play

Lindsey Graham is the incumbent senator and the most recognizable name on the ballot.

Challengers Paul Dans, Mark Lynch, and Thomas Murphy are competing for conservative primary voters and for endorsements from state GOP leaders.

What drives it

Campaign fundraising and endorsements from South Carolina Republican figures materially change expected outcomes.

Turnout, late polling, debate performances, national party attention, and federal policy news that mobilizes voters are the main causal levers.

What to watch

Watch the official primary date, pre-primary debates, and state filing deadlines for shifts in campaign momentum.

Look for weekly fundraising reports, county-level polling, major endorsements from governor or members of Congress, TV ad buys, and turnout patterns on election night.