Arizona Democratic Senate candidate Rep. Ruben Gallego, D-Ariz., speaks at an election night watch party in Phoenix, Tuesday, Nov. 5, 2024. (Ross D. Franklin/AP)

PHOENIX — Democrat Ruben Gallego was elected Arizona’s first Latino senator, defeating Republican Kari Lake and preventing Republicans from further expanding their Senate majority.

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

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

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

Gallego, a five-term member of the House of Representatives and an Iraq War veteran, has a startup life story that he prominently features in his public appearances and advertisements. He will replace Kyrsten Sinema, whose victory as a Democrat in 2018 created the formula the party has successfully copied ever since.

Sinema left the Democratic Party two years ago after antagonizing the party’s left wing. He considered running for a second term as an independent but gave up when it became clear there was no clear path to victory.

“Yes, he could!” Several Gallego fans shouted in Spanish as they made their first comments after the race was called.

“I’m going to fight for Arizona in Washington,” Gallego told cheering supporters, saying he would fight for those who didn’t vote for him as well as those who voted for him.

In his short speech, Gallego mentioned several times the single mother who raised him and said he owed his success to her. He has vowed to work to fix what he says is the nation’s broken immigration system and to continue fighting for veterans and women’s reproductive rights.

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

Gallego ran ahead of Harris, suggesting that a significant number of voters support Trump at the top of the ticket and the Democrat for the Senate; It’s a pattern also seen in Sinema’s victory and Democratic Sen. Mark Kelly’s wins in 2020 and 2022. Ticket splitters also dominated Michigan, Wisconsin and Nevada Senate races this year, with Trump winning their states and Democrats winning as well.

Republicans flipped Democrat-controlled Senate seats in West Virginia, Ohio, Pennsylvania and Montana. In the last three cases, Sens. Bob Casey and Jon Tester, who defeated Sherrod Brown, also ran ahead of Harris but were unable to overcome their state’s shift toward the GOP.

Gallego was comfortably ahead after the first results were announced on election night, but his lead narrowed as more votes were counted. Arizona is notorious for a lengthy count because most people vote by mail, which takes longer to verify and process, including those who drop off their ballots on Election Day.

The son of immigrants from Mexico and Colombia, Gallego was raised by a single mother in Chicago and was eventually accepted to Harvard University. He joined the U.S. Marine Corps Reserve and fought in Iraq in 2005 in a unit that suffered 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 Civil War-era state law that banned abortion in almost all circumstances. Lake was caught in the middle of the issue and opposed the federal abortion ban, infuriating some of her allies on the right.

Gallego portrayed Lake as a liar who would do and say anything to gain power. He downplayed his progressive voting record in Congress and relied on his personal story and military service to craft the image of a pragmatic moderate.

Lake is a well-known former television news anchor who has become a star on the populist right with his 2022 campaign for governor of Arizona.

He never acknowledged losing that race and described himself as the “legal governor” in his 2023 book. Even after launching his Senate campaign, he continued his unsuccessful challenge in court.

His dogmatic adherence to the lie that consecutive elections were stolen from Trump and himself has endeared him to the former president, who is considering him as a vice presidential candidate. But it has further exacerbated his struggle with moderate Republicans, whom he alienated during the 2022 campaign when he snubbed the late Sen. John McCain and then-Gov. Doug Ducey.

He tried to be moderate but struggled to deliver a coherent message on thorny issues like election fraud and abortion.

Lake instead focused on border security, a strong issue for Republicans in a border state that has seen record border crossings during Democratic President Joe Biden’s administration. He promised a tough crackdown on illegal immigration and described Gallego as a supporter of “open borders.” He also went after his personal life, pointing out that he divorced Kate Gallego shortly before she gave birth. His ex-wife, who is now mayor of Phoenix, supported Gallego and campaigned with him.