Nancy Mace's recently departed chief of staff is officially running to throw her out of office

• Nancy Mace has a new GOP primary challenger: her recently departed chief of staff.
• Dan Hanlon, who had worked for Mace since she got to Congress, filed paperwork to run against her.

Dan Hanlon, the former chief of staff for Republican Rep. Nancy Mace, has taken the most official step yet in his bid to run his former boss out of Congress.

On Friday, Hanlon filed the necessary paperwork with the Federal Election Commission to run in the GOP primary in South Carolina's 1st congressional district, which covers Charleston and surrounding areas.

A person familiar with Hanlon's emerging campaign confirmed the veracity of the filing. POLITICO first reported that Hanlon was considering the move.

Hanlon had worked for Mace since she arrived in Congress in January 2021, before being reportedly fired in December 2023.

Hanlon was previously a senior official in the Office of Management and Budget during the Trump administration, and worked for former South Carolina Rep. Mick Mulvaney before that.

It's extremely rare for a lawmaker's former chief of staff to launch a campaign against their one-time boss. Before his departure, Hanlon could often be seen by Mace's side at the Capitol.

According to the Washington Post, former House Speaker Kevin McCarthy — who Mace voted to oust in October — privately encouraged Hanlon to run.

McCarthy notably called Hanlon out during a press conference following his ouster, saying that he had assured the former speaker that he'd "kept your word 100%." Ahead of her vote to oust McCarthy, Mace had publicly claimed that he had broken promises he'd made to her.

It's the latest bad news for Mace, a controversial character whose record of public flip-flopping and perceived camera-hungriness have turned off fellow GOP colleagues.

Despite once being a critic of former President Donald Trump, Mace endorsed him over Nikki Haley — who backed her against a Trump-backed primary challenger in 2022 — earlier this week.

She also faces a Democratic challenger, Michael B. Moore, who has sought to capitalize on her growing cloud of controversy, arguing that Mace is "probably more motivated to get on national TV and create headlines for herself than to actually work for the people."