PHOENIX — Democrat Ruben Gallego has been elected Arizona’s first Latino U.S. senator, defeating Republican Kari Lake and preventing Republicans from further padding their Senate majority.

Gallego’s victory continues a string of Democratic successes for the Senate in a state that was reliably Republican for those seats until Donald Trump was elected president in 2016. Arizona voters had rejected Trump-endorsed candidates in every election since, but the president-elect won Arizona this year over Democratic Vice President Kamala Harris

“Gracias, Arizona!” Gallego wrote on the social platform X.

With Gallego’s win, the GOP will have 53 seats in the 100-member Senate.

Gallego is a five-term House member and an Iraq War veteran with an up-by-the-bootstraps life story that he featured prominently in his public appearances and ads. He will replace Kyrsten Sinema, whose 2018 victory as a Democrat created a formula that the party has successfully replicated ever since.

Sinema left the Democratic Party two years ago after she antagonized the party’s left wing. She considered running for a second term as an independent but bowed out when it was clear she had no clear path to victory.

“Yes, he could!” several Gallego supporters shouted in Spanish as he offered his first comments after the race was called.

“I will fight for Arizona in Washington,” Gallego told the cheering supporters, saying that he would fight as much for the people who did not vote for him as the ones who did.

In his brief remarks, Gallego several times mentioned the single mother who raised him, crediting her with his success. He promised to work to fix what he said was the nation’s broken immigration system, and would continue to fight for veterans and for women’s reproductive rights.

The Associated Press left a voicemail and email message seeking comment from Lake’s campaign Monday night.

With Gallego’s win, there was only one more major race left uncalled in Arizona. The race between Republican Rep. Juan Ciscomani and Democrat Kirsten Engel for the 6th Congressional District remained too early to call.

Gallego ran ahead of Harris, suggesting a substantial number of voters supported Trump at the top of the ticket and the Democrat for Senate, a pattern seen in Sinema’s victory and both of Democratic Sen. Mark Kelly’s wins in 2020 and 2022. Ticket-splitters also were decisive in the Michigan, Wisconsin and Nevada Senate races this year, which Democrats won even as Trump won their states.

Republicans flipped Democratic-controlled Senate seats in West Virginia, Ohio, Pennsylvania and Montana. In the latter three cases, defeated Sens. Sherrod Brown, Bob Casey and Jon Tester also ran ahead of Harris but couldn’t overcome their states’ shifts toward the GOP.

Gallego led comfortably after the first results were released on election night, but his lead narrowed as more ballots were counted. Arizona is notorious for a drawn-out count because most people vote by mail—which takes longer to verify and process—including many who drop off ballots on Election Day.

The son of immigrants from Mexico and Colombia, Gallego was raised in Chicago and eventually accepted to Harvard University. He enlisted in the U.S. Marine Corps Reserve and fought in Iraq in 2005 in a unit that sustained heavy casualties, including the death of his best friend.

Gallego maintained a significant fundraising advantage throughout the race. He relentlessly attacked Lake’s support for a state law dating to the Civil War that outlawed abortions under nearly all circumstances. Lake tacked to the middle on the issue, infuriating some of her allies on the right by opposing a federal abortion ban.

Gallego portrayed Lake as a liar who will do and say anything to gain power. He downplayed his progressive voting record in Congress and leaned on his personal story and his military service to build an image as a pragmatic moderate.

Lake is a well-known former television news anchor who became a star on the populist right with her 2022 campaign for Arizona governor.

She has never acknowledged losing that race and called herself the “lawful governor” in her 2023 book. She continued her unsuccessful fight in court to overturn it even after beginning her Senate campaign.

Her dogmatic commitment to the falsehood that consecutive elections were stolen from Trump and from her endeared her to the former president, who considered her for his vice presidential running mate. But it compounded her struggles with the moderate Republicans she alienated during her 2022 campaign, when she disparaged the late Sen. John McCain and then-Gov. Doug Ducey.

She tried to moderate but struggled to keep a consistent message on thorny topics, including election fraud and abortion.

Lake focused instead on border security, a potent issue for Republicans in a border state that saw record border crossings during Democratic President Joe Biden’s administration. She promised a tough crackdown on illegal immigration and labeled Gallego a supporter of “open borders.” She also went after his personal life, pointing to his divorce from Kate Gallego shortly before she gave birth. His ex-wife, now the mayor of Phoenix, endorsed Gallego and has campaigned with him.