By Gram Slattery

WASHINGTON U.S. House of Representatives Speaker Mike Johnson, the highest-ranking Republican in Congress, endorsed Donald Trump for the Republican presidential nomination on Tuesday, an unsurprising move that underlines the grip the former president holds on much of the party's establishment.

"I'm all in for President Trump," Johnson said on CNBC.

Johnson implied that he had "endorsed" Trump in the past, but it was unclear when he had previously done so. A representative for the speaker did not immediately respond to a request for comment.

Johnson was elected speaker in October after a small group of Republican lawmakers deposed Kevin McCarthy, the previous speaker.

Before that, Johnson led efforts in Congress to overturn Trump's 2020 election loss. Following Trump's defeat, Johnson crafted a legal brief, signed by 125 other House Republicans, that sought to persuade the Supreme Court to reject election results from several contested states Trump had lost to Democrat Joe Biden.

In the CNBC interview, Johnson defended Trump's actions, saying the former president believed "deep in his heart" that the election was fraudulent, an assertion that has been widely disproved.

Johnson still has relatively low name recognition, so it is unclear how much his endorsement will matter to voters. The endorsement nonetheless illustrates how Republican lawmakers have come to embrace Trump, the frontrunner in the Republican presidential nominating contest, even as many had indicated they would look to move on after his 2020 election loss.

(Reporting by Gram Slattery; editing by Andy Sullivan and Jonathan Oatis)