Republican Utah Sen. Mike Lee has a habit of irritating fellow senators when it comes to his “no” votes on broadly popular legislation. 

In 2022, he was the only senator who opposed efforts to create a national historic site at a former Japanese internment site in Colorado. And for every year except one since his 2010 election, Lee has voted against the annual defense authorization legislation, passed yearly with a veto-proof bipartisan majority. His criticism of Washington’s ongoing financial support for Ukraine since Russia invaded the country last year has also put him at odds with the Republican mainstream. 

That obstinance typically doesn’t win many friends in Washington. But it gave him a leading role as just one of just five GOP senators to speak at this week’s marquee Heritage Foundation conference marking the conservative think tank’s 50th anniversary. Heritage has long played an outsized role in shaping Republican policy, but it has lately been distinguishing itself by staking out foreign policy positions at odds with the hawkish national security establishment. 

Lee’s Thursday speech at the conference touted the Constitution as his guidepost on foreign and domestic policy, even if many of his foreign policy positions take him out of the conservative  mainstream. He has argued that the executive branch has long overstepped its constitutional mandates on foreign policy issues and that Congress has not sufficiently stepped up to its role as the entity that can declare war.

“The No. 1 priority for us was looking at something through the lens of the Constitution, so looking through the enumerated powers, figuring out if something was clearly delegated to the executive versus what was clearly a function of Congress,” said Robby Smith Saunders, a former foreign policy advisor to Lee. A spokesperson for Lee did not respond to a request for comment.

What this amounts to in practice is a skepticism of American engagement in foreign conflicts and a broad desire to limit American spending abroad. Just don’t call him an isolationist, his allies say. 

“I think he’s definitely a restrainer. But I definitely would not ever characterize him as an isolationist,” said Saunders.

Still, Lee has often found himself on the outside on major foreign policy issues, particularly on Ukraine. “The American people need to speak up on this and make clear that while we’re concerned about Putin — and Putin’s a bad guy, and I hope sincerely that he’s stopped — this cannot be ours to fight, nor can it be ours to fund alone,” he said on Fox News in February, on the first anniversary of Russia’s invasion. 

This sentiment echoed comments by former President Donald Trump, who has long argued against American support for Ukraine, and Florida Gov. Ron DeSantis, who said in March that getting involved in a “territorial dispute between Ukraine and Russia” is not a “vital national interest” for the U.S. DeSantis later attempted to walk back his comments.

The critical responses from many Republicans indicate that among senior lawmakers, support for continued American military and financial assistance for Ukraine remains strong. “Just because someone claims something doesn’t mean it belongs to them. This is an invasion,” Sen. Marco Rubio (R-FL) said in response to DeSantis’ remarks. Sen. John Cornyn (R-TX) called DeSantis’ comments “disturbing.” 

While Lee’s foreign-policy worldview may have been relatively uncommon among U.S. senators when he was first elected a dozen years ago, his approach to the world has now gained several  powerful ideological allies, Trump chief among them. 

“He’s been very consistent since he was first elected. What is different is that it’s no longer just him and Sen. Rand Paul [R-KY]. It’s that there’s more people that are willing to stand alongside him, particularly on the Republican side, and challenge the prevailing status quo around foreign policy,” said Dan Caldwell, vice president at the Center for Renewing America, a conservative think tank closely aligned with Trump. 

Trump’s embrace of the “America First” banner was a turning point in moving the Republican line from internationalism to a more isolationist approach. Lee doesn’t hew to all the same positions as Trump; for instance, where Trump embraced Saudi Arabia, Lee routinely criticizes Washington’s close relationship with Riyadh, citing Saudi human rights abuses. (Last year, he was the lone Republican to sign onto a letter with progressive Sens. Bernie Sanders (I-VT) and Elizabeth Warren (D-MA) questioning U.S. arms sales to Saudi Arabia and the United Arab Emirates, citing their impact on civilian casualties in the war in Yemen.) But Lee’s overlap with the former president on many other issues is clear.

“I think the future of Republican foreign policy will not deviate much from concepts and principles adopted by Trump, but Republicans will pursue them with a bit more finesse and nuance,” said Bilal Saab, the director of the defense and security program at the Middle East Institute and a former senior advisor at the Department of Defense. 

In the Senate, Lee has found allies in Sens. Josh Hawley (R-MO) and J.D. Vance (R-OH), both of whom also spoke at the Heritage summit this week. 

“I think [L]ee feels like if we’re going to spend this money, we need a rationale for it, or else we shouldn’t be spending it,” said Victoria Coates, a former advisor to Sen. Ted Cruz (R-TX), a close friend and ally of Lee’s. 

This mentality has put Lee at odds with more traditionally hawkish Republicans, who think it is both morally right and in America’s national interest to get involved in some overseas conflicts. 

“The reality is that some investments abroad make Americans safer and more prosperous at home. That reality is not always evident to average Americans busy with their lives. Responsible leaders explain that what America does or does not do abroad matters at home,” said Brad Bowman, senior director of the Center on Military and Political Power at the Foundation for Defense of Democracies, which represents a more interventionist strain of conservative foreign policy. “As Russia, China, and Iran cozy up with one another, it would be pretty foolish for America to neglect its closest friends and allies. We need them more than ever.”

One notable exception to Lee’s approach to foreign spending is Israel. Unlike Rand Paul, an isolationist with whom Lee frequently partners, Lee has not criticized Washington’s $3.3 billion in annual security assistance to Israel. The reason may be that Lee views American support for Israel as strategic for the U.S. — whereas security assistance to Ukraine does not necessarily benefit America, in Lee’s worldview.

“I know in some ways, on a certain level, it seems like maybe an exception to his rules,” said Saunders. “I think for him, what’s so important about Israel is the fact that there’s a mutuality of benefit in terms of R&D, technological capabilities, cooperation when it comes to certain missile-defense programs and knowledge, and he’s driven by his faith.”

Lee traveled to Israel in 2018 for the opening of the U.S. Embassy in Jerusalem, along with Cruz and the more hawkish Sen. Lindsey Graham (R-SC). 

“If you had Mike Lee and Lindsey Graham at the same event, you probably have the full spectrum of conservative national security policy,” said Coates. Lee earned the endorsement of the American Israel Public Affairs Committee’s political action committee in his 2022 reelection campaign. 

The efficacy of the Lee approach, at least in the current Congress, is in question. Neither Congress nor President Joe Biden appears likely to make any major changes to Washington’s aid to Ukraine anytime soon. And while Lee has joined with some progressive Democrats to criticize American support for Saudi Arabia, they are in the minority.

Lee has also been one of the loudest voices seeking an end to the 2002 legislation authorizing the use of military force in Iraq, which he argues has been applied too broadly and for too long. The Senate voted to repeal the 2002 AUMF, and if the House follows, they will hand the Lee camp an ideological victory — but the bill’s future in the House remains uncertain.

Nearly half of Americans (48%) support the U.S. sending weapons to Ukraine, while 29% oppose it, according to an Associated Press-NORC poll from February. But Americans are divided on whether the U.S. should directly send government funds to Ukraine. Support for both policies has decreased since last year, when the AP found that 60% of Americans supported sending weapons to Ukraine. 

“I think that more of the country is probably now in alignment with [Lee’s] position on issues than even when I worked for him five years ago,” noted Saunders.