Republican Congresswoman Nancy Mace of South Carolina is set to endorse Rep. Ralph Norman in the race to fill the US Senate seat left vacant by the death of Senator Lindsey Graham, breaking with President Donald Trump, who is backing a different candidate. The move is notable because it pits Mace publicly against Trump's preferred choice and against a former rival, adding to the unpredictability of what is already shaping up to be a chaotic special election in South Carolina.

Mace, who is herself running for South Carolina governor, described the contest as a "once-in-a-generation opportunity" to send a committed conservative to the Senate. The endorsement highlights a rift within the state's Republican ranks over who should succeed the late Senator Graham, with the eventual nomination process likely to be closely watched given the competing loyalties to Trump and to local political alliances.