Curtis defeated Democrat Caroline Gleich, a mountaineer and environmental activist from Park City, in a race that often centered around each candidate’s climate policies. The incoming senator leads the Conservative Climate Caucus on Capitol Hill and has developed a reputation for pushing back against party leaders such as Donald Trump who falsely claim that climate change is a hoax.

He will succeed one of Washington’s most prominent centrists and an outspoken critic of Trump.

Curtis took the stage with his wife, children and grandchildren at a lively watch party Tuesday night in Provo, the city where he was once mayor, to speak to supporters after his victory.

“You elected me to legislate, to advocate and represent you,” Curtis said. “My agenda will be your agenda. My voice will lift your voice. My vote will reflect your values. And, together, we’ll make Washington more like Utah.”

“I hope that you’ll see in my actions the dignity of working together and of unity,” he added. “As Utah’s senator, I will make this model my mandate.”

Curtis, 64, began his political career as a county-level Democratic Party official. He is the longest-serving member of Utah’s U.S. House delegation and is viewed as a moderate in the manner of Romney.

The incoming senator said he plans to carve out his own brand of conservatism in the post-Romney era of Utah politics, with a focus on bringing Republicans to the table on issues involving climate change.

Romney congratulated Curtis on his win Tuesday night, calling him a man of honor and integrity who puts others before himself.

“John Curtis has admirably represented the interests of Utahns in the House, and I have no doubt he will continue to do so in the Senate,” Romney said in a statement on the social media platform X. “Our country needs more leaders like him.”

In the June primary, Curtis emerged from a crowded pool of candidates to defeat a Trump-backed mayor. He said Tuesday night that he voted for Trump, sticking with his early pledge to vote for the ultimate Republican presidential nominee.

His climate caucus takes a market-based approach to environmental issues, countering Democratic policies with proposals that Curtis has said aim to lower emissions without compromising American jobs and economic principles. Gleich had accused him of pandering to the fossil fuel industry instead of supporting policies she said are needed to protect public lands, air and water.

At his watch party, Curtis treated friends and family to live music and local food vendors. On their way out the door, each attendee received a pair of socks picturing Curtis with Utah’s iconic Delicate Arch in Arches National Park.

The state has not elected a Democrat to the Senate since 1970.

Gleich congratulated Curtis in a statement while saying she was proud of the campaign she ran and looked forward to working with Curtis to help protect the environment.

“While the result was not what we had hoped, we focused on critical issues: climate action, public lands and reproductive freedom,” Gleich said.

Curtis told reporters that Gleich is one of the hardest working people he has met in Utah, and he commended her for putting so much heart into her campaign.

Moderate Republicans like Curtis tend to prevail in statewide elections in Utah.

Members of The Church of Jesus Christ of Latter-day Saints, who make up about half of the state’s 3.4 million residents, have been a reliably Republican voting bloc for decades. But many have been hesitant to embrace Trump and his allies, saying the former president’s brash style and comments about immigrants and refugees clash with their religious beliefs.

Republican Mike Kennedy also won election to the open U.S. House seat Curtis is vacating. Kennedy handily defeated Democrat Glenn Wright in the 3rd Congressional District, which spans eastern Utah and includes the cities of Orem and Provo. This will be Kennedy’s first term in Congress after serving in the state Legislature since 2013.