Former Democratic Rep. Tulsi Gabbard is Trump's pick for director of national intelligence

Tulsi Gabbard -- a military veteran and honorary co-chair of President-elect Donald Trump's transition team -- has been chosen by Trump to be his director of national intelligence.

Gabbard left the Democratic Party in 2022 after representing Hawaii in Congress for eight years and running for the party's 2020 presidential nomination. She was seen as an unusual ally with the Trump campaign, emerging as an adviser during his prep for his debate with Vice President Kamala Harris, who Gabbard had debated in 2020 Democratic primaries.

"For over two decades, Tulsi has fought for our Country and the Freedoms of all Americans. As a former Candidate for the Democrat Presidential Nomination, she has broad support in both Parties - She is now a proud Republican!" Trump said in a statement announcing his pick, which will need to be confirmed by the Senate.

Before the announcement, Gabbard said it would be a "honor" to serve in a Trump administration as she waited for Trump to make selections for his administration.

"If there's a way I can help achieve the goal of preventing World War III and nuclear war? Of course," she said in an interview with NewsNation on Monday night.

She advocated for war to be the "last resort."

"Trump ended up with some neocons around him who were trying to undermine his objectives so they could feed their goals of continuing to keep us in a perpetual state of war," Gabbard said, discussing his first administration. "This administration has us facing multiple wars on multiple fronts and regions around the world and closer to the brink of nuclear war than we ever have been before," Gabbard said when she endorsed Trump during a campaign event in Michigan.

"This is one of the main reasons why I'm committed to doing all that I can to send President Trump back to the White House, where he can, once again, serve us as our commander in chief."

Gabbard has, in recent years, strengthened her ties with Republicans in the House and the Senate. Two of her closest allies from her early days in Congress are Arizona Sen. Kyrsten Sinema, a Democrat turned independent, and Oklahoma Republican Sen. Markwayne Mullin. Gabbard and Mullin even hit the campaign trail together earlier this year, joining "Team Trump on Tour" to support Trump's campaign.

Kentucky GOP Sen. Rand Paul has also formed an unlikely alliance with Gabbard, collaborating on the Stop Arming Terrorists Act in both the House and Senate -- a nod to her stance against the “military-industrial complex.”

In 2020, as the Democratic presidential field narrowed to three candidates, Gabbard described her bid as “an opportunity to speak to Americans every single day about the sea change we need in our foreign policy.”

Throughout Trump's campaign, Gabbard played an active role, whether it was moderating town halls, touring with the group Women for Trump, or mingling throughout Mar-A-Lago.

Gabbard's appearances highlighted that the coalition of supporters around Trump had shifted. The campaign pointed to Gabbard and former Democratic and independent presidential candidate Robert F. Kennedy Jr. to signify the change in his upcoming administration.

Gabbard said in April she had turned down Kennedy's offer to be his running mate after meeting with him several times. A person close to him told ABC News, "There were definitely meetings, but it didn't work out."

ABC News' Beatrice Peterson contributed to this report.