During a question and answer session after delivering a speech at the Hudson Institute in Washington, D.C., on Wednesday, Haley was asked who she thinks would do a better job in the White House with national security issues: Joe Biden or Donald Trump.

The former United Nations ambassador said she prioritizes a president who will hold enemies to account, secure the border and support "capitalism and freedom" -- and that while "Trump has not been perfect on these policies," that "Biden has been a catastrophe."

"So I will be voting for Trump," Haley said.

Haley suspended her campaign in March.

During a speech announcing her campaign suspension -- the day after suffering considerable losses on Super Tuesday, the former South Carolina governor said Trump had to "earn the votes."

"It is now up to Donald Trump to earn the votes of those in our party and beyond it, who did not support him," she said in March. "And I hope he does that. At its best politics is about bringing people into your cause, not turning them away. And our conservative cause badly needs more people."

Many of the Republicans who once challenged Trump for the nomination quickly fell into line behind him after exiting the race.

The Biden campaign has tried to court Haley voters, some of whom have told ABC News they remain undecided.

On Wednesday, following Hayley's announcement, a rep for the Biden campaign released a statement touting their candidate.

"Nothing has changed for the millions of Republican voters who continue to cast their ballots against Donald Trump in the primaries and care deeply about the future of our democracy, standing strong with our allies against foreign adversaries, and working across the aisle to get things done for the American people – while also rejecting the chaos, division and violence that Donald Trump embodies," the statement read. "Only one candidate shares those values, and only one campaign is working hard every day to earn their support – and that's President Biden's."