Trump transition: Trump announces Matt Gaetz as attorney general, Marco Rubio as secretary of state

Trump announced his senior staff on Wednesday, bringing back some of his well-known names from his first term and those who helped on his campaign.

Dan Scavino, one of Trump's long-time allies, was named assistant to the president and deputy chief of staff. Stephen Miller was named assistant to the president and deputy chief of staff, a move reported earlier this week.

James Blair, the Republican National Committee political director and campaign aide, has been named assistant to the president and deputy chief of staff for legislative, political and public affairs. Taylor Budowich will serve as assistant to the president and deputy chief of staff for communications and personnel. He was a senior member of several of Trump's PACs.

Senate Republicans on Wednesday elected John Thune to be the next Republican leader, succeeding Mitch McConnell in a position he's held for 17 years.

Thune beat out Sen. John Cornyn in a second round of votes, securing enough to clinch the position.

This was by secret ballot and behind closed doors. Thune is expected to address the press at a press conference later today.

President-elect Donald Trump is moving quickly to install loyalists and allies into his administration. But he's struggling with making a decision on one of his top law enforcement positions: attorney general, multiple sources told ABC News.

Trump interviewed multiple candidates for attorney general on Tuesday, but he came away unsatisfied, sources with knowledge of the conversations told ABC News.

Trump interviewed Missouri Attorney General Andrew Bailey on Monday, and sat down with lawyers Jay Clayton and Bob Giuffra about the post, sources said. No final decision has been made, sources said.

Notably, billionaire Elon Musk has been involved in -- and sitting in on -- interviews with potential attorney general candidates, the sources said.

In a sign of how quickly other positions are moving, Pete Hegseth -- the Fox News host selected as the nominee for Defense Secretary -- was just called Monday and interviewed for the position Tuesday, a source familiar told ABC News.

Within hours, Trump made his choice, sources added. Several Republicans on Capitol Hill and even some Trump allies described being "caught off guard" by the pick.

-Katherine Faulders, Will Steakin, Rachel Scott, John Santucci

Elon Musk is expected to join President-elect Donald Trump today in Washington, sources tell ABC News.