Tulsi Gabbard, the director of national intelligence, submitted a letter of resignation to President Trump on Friday, saying that she was stepping away to support her husband after he recently was diagnosed with a rare form of bone cancer.

The departure will bring to an end Ms. Gabbard’s rocky tenure overseeing the 18 U.S. intelligence agencies. She had been largely sidelined by the White House on significant national security issues, including Iran and Venezuela.

Ms. Gabbard, 45, said she would remain in her post as the nation’s intelligence chief until June 30.

“My husband, Abraham, has recently been diagnosed with an extremely rare form of bone cancer,” Ms. Gabbard said in her resignation letter, a copy of which was released by her office. “He faces major challenges in the coming weeks and months. At this time, I must step away from public service to be by his side and fully support him through this battle.” Ms. Gabbard has been married to Abraham Williams, a cinematographer, since 2015.

Mr. Trump announced that Aaron Lukas, Ms. Gabbard’s deputy, would serve as acting director of national intelligence.

Ms. Gabbard, a former Democratic congresswoman who ran for president in 2020 before breaking with her party to support Mr. Trump in 2024, had been a controversial figure in the Trump administration after narrowly being confirmed by the Senate last year. She was seldom seen in the room when Mr. Trump made major national-security decisions and was widely viewed within the administration and by lawmakers in Congress as not a key member of the president’s national-security team.

In a post on Truth Social, Mr. Trump thanked her for her service in the administration.

“Tulsi has done an incredible job, and we will miss her,” he wrote.

Ms. Gabbard has had an up and down relationship with the White House, but she has managed her relationship with Mr. Trump, and won support from him with her work on election security and her appearance early this year at an F.B.I. seizure of 2020 vote ballots in Georgia.

And Ms. Gabbard pleased Mr. Trump with her criticism of Obama-era investigations of Russia election meddling. “She’s, like, hotter than everybody. She’s the hottest one in the room right now,” Mr. Trump said last July, after Ms. Gabbard amplified without evidence claims that the Obama administration had deliberately overstated Russia’s interference in the 2016 election.

But Ms. Gabbard had difficult relations with the C.I.A., and she was viewed unfavorably within parts of the White House as well as the broader U.S. intelligence community, according to current and former American officials. She presided over significant turnover at her agency headquarters in Liberty Crossing, Va., and supported efforts by Mr. Trump to rescind security clearances of intelligence officials viewed by the president and his allies as either disloyal or corrupt.

The problems for Ms. Gabbard began soon after she was confirmed to the job last year following an especially contentious confirmation hearing, where several Republican senators joined Democrats in aggressively questioning her about some of her past views, including her defenses of the former intelligence contractor Edward Snowden and Bashar al-Assad, the former Syrian dictator.

Olivia C. Coleman, a spokeswoman for Ms. Gabbard, challenged accounts that Ms. Gabbard was at odds with the White House.

Ms. Gabbard will be the fourth Cabinet member of Mr. Trump’s second term to step down, following former Attorney General Pam Bondi, former Homeland Security Secretary Kristi Noem, and former Labor Secretary Lori Chavez-DeRemer. All four of them are women.

A close aide and ally to Ms. Gabbard, Joe Kent, stepped down in March as the top U.S. counterterrorism official, citing objections to the Iran war.