South Dakota Sen. John Thune, the No. 2 Senate Republican, plans to endorse South Carolina Sen. Tim Scott's bid for the 2024 GOP presidential nomination, according to two sources familiar with the plans.

Scott, who has already filed his candidacy with the Federal Election Commission, will formally kick off his campaign Monday in North Charleston, South Carolina, and Thune is expected to deliver the opening prayer at the event, the sources said.

Thune had previously encouraged Scott to enter the contest, pushing him to visit the early-voting state of Iowa and telling CNN in March that his colleague would be "a great candidate."

"He's really well thought of and respected," Thune said. "I think he'd be a really interesting candidate for president in a field that ... could be fairly open."

Scott, the only Black Republican in the Senate, joins a growing GOP field looking to challenge President Joe Biden as he seeks a second term.

Former President Donald Trump is making a third run for the White House. Former South Carolina Gov. Nikki Haley, who appointed Scott to his Senate seat a decade ago, launched her campaign in February. Others in the GOP race include former Arkansas Gov. Asa Hutchinson, tech entrepreneur Vivek Ramaswamy and talk radio host Larry Elder.

Florida Gov. Ron DeSantis is also expected to enter the contest this week.

Scott launched a presidential exploratory committee in April, emphasizing his evangelical faith, his race and his experience growing up as the son of a single mother. He defined his personal ethos as one of "individual responsibility" and said his approach to politics was guided by the belief that the US is "the land of opportunity and not the land of oppression."

Thune isn't the only Republican who has spoken positively of Scott's strengths in a presidential race. Speaking to CNN's Jake Tapper on "State of the Union" on Sunday, Louisiana Sen. Bill Cassidy called Scott a "pretty formidable candidate."