Sen. Tim Scott (R-S.C.) is planning to endorse former President Trump at a rally in New Hampshire on Friday, according to a person familiar with the matter.

Why it matters: The expected move by the former GOP presidential hopeful comes after Trump and former UN Ambassador Nikki Haley fought for Scott's endorsement ahead of the New Hampshire primary.

• It's a blow to Haley, a fellow South Carolina Republican, who is hoping to catch Trump in 2024's first-in-the-nation primary on Tuesday and break his momentum following a dominant win at the Iowa caucuses.

The big picture: Scott, who Haley appointed to the Senate when she was governor, is the latest prominent Republican to get behind Trump after his 30-point win in Iowa.

• Sen. Ted Cruz (R-Texas), Trump's rival in the 2016 primary, also endorsed the former president after Iowa.
• Other former GOP presidential hopefuls, including Vivek Ramaswamy and North Dakota Gov. Doug Burgum, have all also backed Trump this month.
• The New York Times first reported on Scott's plans.

Zoom in: Scott said in November when he suspended his campaign that he was not going to make an immediate endorsement.

• "The best way for me to be helpful is to not weigh in on who they should endorse," he said in November.

What they're saying: "Interesting that Trump's lining up with all the Washington insiders when he claimed he wanted to drain the swamp," a spokesperson for Haley said in a statement.

• "But the fellas are gonna do what the fellas are gonna do."

A spokesperson for Trump's campaign did not immediately respond to Axios' request for comment.

Go deeper: Tim Scott's big spending gamble

Editor's note: This is a developing story. Please check back for updates.