Elbridge Colby, tapped by Trump to be undersecretary of defense for policy, is set to be grilled Tuesday by the Senate Armed Services Committee as GOP senators seek assurances from the White House and Colby about his past comments on the Middle East, particularly Iran.

“We’re going to have a hearing and see what we can find out,” said Sen. Roger Wicker (R-MS), chairman of the Armed Services panel.

He declined to comment further about Colby’s nomination, only to say that he anticipates senators will receive “a lot of clarity.”

Sen. Tom Cotton (R-AR), who’s expressed his concerns to the White House and sits on Armed Services, chairs the Senate Intelligence Committee, and is the Senate Republican Conference Chairman, has been accused of trying to tank Colby behind the scenes, most notably by Turning Point USA founder Charlie Kirk.

The apprehensions from them and other Republicans have been sparked predominantly by Colby’s positions that the United States should redirect its attention from threats in the Middle East, such as countering Iran and its proxies, to instead focus on China and its growing influence in Asia.

He’s also advocated for pulling back from Russia’s war against Ukraine, downplayed the risks of Iran obtaining a nuclear weapon and that it would be “eminently plausible and practical” to contain, and opposed U.S. strikes on Iran against its nuclear program because it would be worse than allowing them to obtain a nuclear weapon.

Colby’s more isolationist views have played well among the MAGA base and conservative senators who more closely align with Trump’s similar worldviews. But more traditional foreign policy hawks, many of whom staunchly back U.S. aid to Ukraine, are facing significant heartburn.

Billionaire Trump ally Elon Musk has also piled onto Cotton, who himself has close ties to Trump. Vice President JD Vance, who helped shepherd other controversial nominees through the Senate, and Donald Trump Jr. have publicly endorsed Colby.

Cotton has raised red flags to the White House about Colby’s past comments on Iran and will meet privately with the nominee on Monday ahead of Tuesday’s confirmation hearing, according to a source close to the senator.

“Cotton’s point to the administration is he doesn’t expect nominees to agree with him on everything,” the source said. “But on critical issues, he wants assurances that they support Trump’s policy, and he sees this issue — nuclear-armed Iran — as one of those crucial issues.”

Sen. Joni Ernst (R-IA) signaled she also has outstanding concerns with Colby’s Middle East policies.

“Those are the questions that we’ll ask him, and hopefully he’ll clarify that,” Ernst said.

With Democrats on the committee expected to unite in opposition to Colby, he’ll likely require the support of all Republicans to advance to the full chamber.

“I have deep and grave concerns about a record of views that are totally antithetical to a strong national defense, in my view,” Sen. Richard Blumenthal (D-CT) said. “A nuclear-armed Iran is a dagger at the heart of the United States’ security and the region, and I have strong concern about his comments on Iran.”

A representative for Colby did not respond to requests for comment.

Other Senate Republicans on Armed Services who’ve had conversations with Colby downplayed his past remarks as cherry-picked or taken out of context. Additionally, they expressed confidence that he’ll carry out Trump and the administration’s foreign policy agenda, which does not align with Colby’s positions on Iran.

Colby is a former Pentagon official who served as deputy assistant secretary of defense for strategy and force development in Trump’s first term.

“I’m well aware of his comments. My thing about that is, we’ve dealt with that issue with [Secretary of Defense Pete Hegseth], [Director of National Intelligence Tulsi Gabbard], and [Health and Human Services Secretary Robert F. Kennedy Jr.],” Sen. Markwayne Mullin (R-OK) said. “What you said in the past, we can work past it, because positions change.”

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Sens. Rick Scott (R-FL), Tim Sheehy (R-MT), and Tommy Tuberville (R-AL) expressed approval for Colby.

“Everybody’s got problems,” Tuberville said. “I’m satisfied with all of his answers. A lot of these people make a mountain out of a molehill over one little piece of statement that they made. He’s going to be 100% behind President Trump’s agenda, so that’s the main thing.”