President Biden won the South Carolina Democratic primary on Saturday, AP projects, in the Palmetto State's inaugural run as the first state on the official Democratic primary calendar.

Why it matters: Biden was expected to coast to victory in South Carolina, but the contest was a first test of his momentum as polls show him struggling to generate enthusiasm.

The big picture: A Biden write-in campaign won the Democratic primary in New Hampshire, but the South Carolina primary was the first contest that Biden filed to appear on the ballot.

• Biden in the run-up to the February primary ramped up his campaigning in South Carolina to boost turnout in the state that helped carry him to the White House in 2020.
• He has been trying to make inroads with Black voters as polls show him underperforming with this important voter bloc.

Zoom in: The DNC last year made South Carolina the nation's first primary state, a move that Biden supported to give states with more racial diversity a greater say in the contest.

• The Biden campaign has already signaled that they are focused on the general election, presenting the contest in stark terms as a choice between Biden and former President Trump.

Go deeper: Biden will target Trump in speech at war site on Jan. 6 anniversary