An Arizona border county sheriff this week endorsed Democrat Ruben Gallego over Republican Kali Lake in the state's Senate race that could determine which party controls the U.S. Senate after November.

Lake, who gained attention during his unsuccessful bid for governor in 2022, has made immigration a key part of his Senate campaign, as Arizona is one of several border states that have seen an increase in migrant inflows in recent months. Immigration and border security, seen as a sore spot for President Joe Biden and the Democratic Party, are also likely to be key issues in the election in Arizona, a battleground state that is roughly evenly split between Democrats and Republicans.

Gallego, who represents a Phoenix congressional district, got a boost in his campaign with the endorsement of Santa Cruz County Sheriff David Hathaway.

Hathaway said in a statement first published in the media: Washington Examinerpraised Gallego as a “longtime ally of Arizona's border law enforcement agencies and communities, and a tireless advocate for providing much-needed funding to maintain a safe and profitable border.”

He criticized other politicians who “simply exploit the idea of ​​borders for personal political gain,” but said Gallego was different.

“Arizona's border communities and law enforcement need Ruben Gallego to be a U.S. Senator, and I'm proud to support his campaign,” Hathaway added.

Santa Cruz County, with a population of just over 49,000, lies south of Tucson along the U.S.-Mexico border. It is the most Democratic county in a key battleground state, with Biden receiving more than 67% of the vote in the 2020 election. The county is home to the border city of Nogales, the port of entry into Mexico.

According to data from U.S. Customs and Border Protection, there have been more than 250,000 encounters in the agency's Tucson division, which includes Santa Cruz County, so far in fiscal year 2024, which began in October.

Newsweek Seeking comment, Lake's campaign was contacted by email and Hathaway's office was contacted via a contact form.

Arizona's Senate primary is scheduled for July 30, with polls showing Gallego and Lake expected to win their party's nomination.

Gallego touted Hathaway's endorsement, post to X, the social media platform formerly known as Twitter.

“Keeping Arizonans safe will always be my number one priority, which is why I'm honored to have the support of Sheriff @JamesDavidHath1. Sheriff Hathaway is a partner when it comes to ensuring Santa Cruz County is a safe place to live, work and visit, and providing solutions to Arizona's border communities. I look forward to continuing to work together to create a safer and more prosperous Arizona,” he wrote.

But Lake Criticized Gallego's record on immigration issues.

“@RubenGallego and @JoeBiden want to protect the feelings of those who enter our country illegally and bring us harm. I want to protect our sons and daughters from the senseless violence that results from people like Ruben and Biden choosing not to enforce our immigration laws,” she posted on X on Wednesday, referring to some Democrats taking issue with Biden calling the immigrants who allegedly killed Georgia college student Laken Riley “illegal” in his State of the Union address.

Polls show the race between Gallego and Lake is tight. They are vying to replace Sen. Kyrsten Sinema, a Democrat-turned-independent who said she won't run for reelection.

The Rasmussen Reports survey of 1,001 voters conducted Feb. 21-26 found that 45% of respondents said they would vote for Lake, a Republican, and 42% said they would support Gallego, giving Lake a slight lead. The poll has a margin of error of plus or minus 3 percentage points.

But an Emerson College poll of 1,000 likely voters conducted Feb. 16-19 found that 46% of respondents planned to vote for Gallego and 39% supported Lake. The poll had a margin of error of plus or minus 3 percentage points.