By Jennifer Hansler, CNN

(CNN) — Former national security adviser Mike Waltz defended his use of the messaging app Signal during a Tuesday confirmation hearing where lawmakers largely avoided the topic.

The “Signalgate” scandal, in which top Trump administration officials discussed sensitive details of a US military strike in a chat to which Waltz had inadvertently added a journalist, dominated headlines and led to his ouster as national security adviser in May. Waltz was instead nominated as US ambassador to the United Nations.

However, during Waltz’s confirmation hearing for the ambassador role Tuesday, only a few Democrats on the Senate Foreign Relations Committee raised the matter, and only one explicitly said he would not support Waltz’s nomination.

Instead, the hearing was largely dominated by questions about how Waltz plans to approach the international organization. The Trump administration has vilified the UN as ineffective, accused it of being anti-Israel and proposed cutting billions of dollars in US funding for its operations, including for peacekeeping.

On the matter of Signalgate, Waltz maintained that none of the sensitive details shared in the chat were classified.

“We followed the recommendation, almost the demand, to use end-to-end encryption, but there was no classified information shared,” Waltz said during an exchange with Democratic Sen. Chris Coons.

Waltz, a former Florida lawmaker, said the White House had investigated the matter and there was no resulting disciplinary action. The Pentagon’s probes are ongoing, he said.

Asked by Democratic Sen. Tim Kaine whether the Pentagon investigations had concluded the information was not classified, Waltz said he couldn’t comment on an ongoing investigation.

“I can echo Secretary Hegseth’s testimony that no names, targets, locations, units, routes, sources, methods, classified information was shared,” he said, referring to Defense Secretary Pete Hegseth.

After the hearing, both Coons and Kaine suggested they were not satisfied by Waltz’s answers on Signal. Neither would say whether they will vote for him.

Democratic Sen. Cory Booker told Waltz that he was “really disappointed” and troubled by “your failure to just stand up and take accountability for mistakes that you made and that all Americans know that you’ve made.”

“I cannot support your nomination. I think you’ve shown failure of leadership at a time that America especially needs people of honor to stand up and show what leadership actually is,” Booker said.

Sen. Jeanne Shaheen, the top Democrat on the Senate Foreign Relations Committee, said after the hearing that she hadn’t decided if she will support Waltz’s nomination.

“I disagree with some of his answers so far,” such as “how important it is for the United States to participate in international bodies,” she told CNN’s Manu Raju. “He went a ways towards agreeing with that. I would like to explore some of his answers a little more.”

Waltz is the administration’s second nominee for the UN role, after New York Rep. Elise Stefanik’s nomination was pulled by the White House amid concerns over slim GOP margins in the House.

Waltz told lawmakers he believes the UN is in need of reform but also has potential.

“We should have one place in the world where everyone can talk, and where China, Russia, Europe, the developing world, can come together and resolve conflicts, but after 80 years, it’s drifted from its core mission of peacemaking,” he said.

“I’m confident we can make the UN great again,” he said.

This story has been updated with additional details.

CNN’s Manu Raju and Alison Main contributed to this report.

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