Sen. Steve Daines participates in a Finance Committee hearing on Wednesday, March 22, 2023.
CNN  — 

Montana Sen. Steve Daines, the head of the Senate GOP’s campaign arm, endorsed former President Donald Trump Monday night.

“The best four years I’ve had in the US Senate is when President Trump was serving in the Oval Office,” Daines told Donald Trump Jr. on Trump’s Rumble show, “Triggered.”

“You talk about results – we passed and he signed the greatest tax cut in American history. We transformed the courts – the Supreme Court, the circuit courts. … We had a country that was respected and strong,” said Daines, the chairman of the National Republican Senatorial Committee. “I am proud to endorse Donald J. Trump for President of the United States.”

As head of the NRSC, Daines’ job is to help Republicans win the Senate in 2024. The party, which currently holds a narrow 51-49 majority, must defend 23 of the 34 seats up for grabs this cycle. That means Republicans need a net gain of just one or two seats to retake the Senate, depending on which party wins the White House in 2024.

One source close to the Trump campaign described the endorsement as not only a political win, but a financial win as well. In his role, Daines has access to a vast network of wealthy Republican donors, many of whom have attempted to distance themselves from the former president this cycle. There is a hope, according to this source, that Daines’ endorsement could help boost Trump’s fundraising.

After the 2022 midterms, when there was some consternation among GOP leaders over Trump’s backing of untested candidates, the NRSC under Daines has taken a much more hands-on approach to primaries, actively working on candidate recruitment and vetting.

As CNN previously reported, the NRSC is weighing whether to spend big bucks in primaries to help root out weaker candidates, a move that risks setting up a clash with hard-right candidates aligning themselves with Trump. The GOP’s best pick-up opportunities lie in three states Trump won where Democratic senators are up for reelection next year, including Daines’ home state of Montana.

Privately, Daines has spoken multiple times with Trump and has been in touch with his eldest son. The goal, GOP sources told CNN earlier this month, is to keep Trump aligned with Republican leadership – even as the former president has furiously attacked Senate Minority Leader Mitch McConnell in the aftermath of the US Capitol attack on January 6, 2021, and as the Senate GOP leader has stayed silent amid the former president’s indictment on 34 felony charges in New York. Daines, however, has been vocal in his defense of Trump.

This story has been updated with additional information.

Manu Raju and Alayna Treene contributed to this report.