The Republican lead in voter registration in a key Arizona county has increased sharply since 2020, while the state remains hotly contested in the 2024 presidential race between Vice President Kamala Harris and former President Donald Trump.

Arizona is a crucial swing state in this year’s election. The state narrowly supported President Joe Biden in 2020 after voting Republican in every other presidential contest since 2000. Polls have shown a tight race in the state since Harris emerged as the Democratic nominee, replacing Biden, amid concerns about whether he could mount a successful presidential campaign and beat Trump in November.

Maricopa County, home to Phoenix, the state’s largest city, will be crucial to how Arizona votes in November. It will be one of the most closely watched counties in the United States in November. Over half of Arizona’s residents live in Maricopa County, and strong Democratic performance in the county won the state for Biden in 2020.

Biden won Maricopa County by about two percentage points, while he won statewide by just 0.3 percentage points. Biden won both the county and the state largely because he appealed to independent suburban voters who could again determine the outcome of the election.

However, new voter registration data from Arizona suggests that Democrats have lost votes in the county since 2020, while Republicans have seen gains in the number of voters who identify with their party.

Data from July 30 show that in Maricopa County, 692,294 voters identified themselves as Democrats, 851,227 as Republicans, and over 800,000 others as supporters of another party or as independents.

Data from August 4, 2020 showed that 764,774 voters identified themselves as Democrats, while 849,313 identified themselves as Republicans. Over a four-year period, 72,480 voters switched their affiliation away from Democrats, while Republicans gained 1,914 new voters over the same period.

Newsweek has emailed Harris and Trump’s campaign teams for comment.

What’s particularly notable is that more than 800,000 voters in the county still identify as neither Democrat nor Republican. They will play a crucial role in the upcoming election as Harris and Trump battle for the support of these swing voters.

Republicans have the advantage in nationwide voter registration numbers, but polls still point to a neck-and-neck race between Harris and Trump.

Statewide, approximately 1.29 million voters are registered as Democrats, 1.39 million as Republicans, and 1.3 million are not registered with any party.

A New York Times/A poll of 677 likely voters conducted at Siena College from August 8-15 found Harris leading Trump by 5 percentage points in Arizona (50 percent to 45 percent).

Meanwhile, a Noble Predictive Insights poll of 1,003 registered voters conducted August 12-16 found Trump leading by three percentage points (47 percent to 44 percent).

According to polling data from FiveThirtyEight, the race is nearly even, with Harris holding a slim 0.8-point lead over Trump. A RealClearPolitics average gives Harris a 0.6-point lead.