South Carolina’s Republican contest to fill the late Lindsey Graham’s Senate seat is becoming a test of President Donald Trump’s influence within the party. Trump has backed newly appointed Senator Darline Graham, Lindsey Graham’s sister, but several Republicans are continuing to pursue the nomination, suggesting that his endorsement may no longer deter challengers as reliably as before.

Darline Graham announced she would seek a full term after being appointed to complete her brother’s term and receiving Trump’s support. Her candidacy is politically untested, and she may also face questions over a state Republican Party rule requiring candidates to have voted in at least two of the previous three statewide GOP primaries.