(NewsNation) — Arizona will again play a key role in determining who wins the White House, but even within its borders, the state has remained a battleground when it comes to its purple-shaded political landscape.

The fortunes of former President Donald Trump and Vice President Kamala Harris could be won or lost by which way Arizona’s voters lean. But in a state where Republicans, independents and Democrats are divided by a total of six percentage points, a host of ballot proposals ranging from the constitutionality of abortion, the border and the economy will also likely be decided by razor-thin margins.

Arizona voters have made elections a virtual toss-up thanks to a diverse electorate that has become more urban in recent years, says Sarama Klar, a professor of political science at the University of Arizona’s School of Government and Public Policy.

About 60% of state residents reside in Maricopa County, which is home to Phoenix. In recent years, the state, where a majority of registered voters are Republicans, has trended liberal, with the offices of governor, attorney general and state senators held by Democrats.

But even that is closely contested, with 35.41% of registered voters identifying as Republicans compared with 29.1% Democrats and 33.95% others, making the state’s election results across the board unpredictable, Klar told NewsNation.

“People talk about, ‘Do you think abortion is going to make the difference? Do you think the economy is going to make the difference?’” Klar said. “I think there’s a cloud in the sky that could make the difference.

“I don’t think you can ask me about any factor and have me say, ‘Oh, that’s really not going to make a difference.’ Every voting bloc matters, every voter matters, every issue matters.”

Why is Arizona’s electorate unique?

Given the tightness of elections, voter engagement remains high among Arizonans, 90% of whom vote by mail, Klar said.

However, voter registration has become an issue as the Maricopa County Recorder’s Office announced that nearly 97,000 people registered to vote without proof of citizenship and may not be eligible to vote. The largest group of affected voters are Republicans, the county recorder said. The affected voters are most likely U.S. citizens who just don’t have documented proof, Fox10 in Phoenix reported.

The Arizona Supreme Court recently ruled that those voters who were unable to verify their citizenship are indeed eligible to vote in the upcoming election.

In addition to abortion, the economy and inflation remain at the top of mind for Arizonans, who have seen the cost of living in the state jump over the past decade.

With more residents moving from rural areas to urban cities like Phoenix and the surrounding area, obtaining a mortgage or covering rent is most concerning for residents regardless of their party affiliations. Klar said.

Despite a recent trend of Democratic success, the number of registered Republicans has not diminished. Rather, the candidates themselves, especially those with GOP leanings, have shifted with Democrats doing a better job of adjusting the centrist views of many Arizona voters, Klar said.

In the 2020 election, U.S. Sen. Mark Kelly, a Democrat and retired astronaut and U.S. Navy captain, collected more votes than then-Democratic nominee Joe Biden, who defeated then-President Donald Trump by 0.35 percentage points.

The current race for U.S. Senate, which pits Democratic U.S. Rep. Ruben Gallego against Trump-backed Republican Kari Lake, could garner more attention than the presidential race, Klar predicted. Like most Arizona elections, the push for the White House is expected to be neck-and-neck, which mirrors the national race.

After Arizona held red for decades, the recent shift in the other direction again places an interesting spotlight on Arizona, Klar said.

“That’s a blue wave that could give off the impression that Arizona has undergone some transformation,” she said. “That could go away, but at this point, I think Arizona is going to be solidly purple. I think we are going to go back and forth.”

Which Arizona ballot measures could lean red or blue?

The top ballot issue is Proposition 139, the ‘Right To Abortion Initiative,’ which would amend the state’s constitution to enshrine abortion access as a fundamental right.

The measure comes after the Arizona Supreme Court upheld an 1864 trigger law that prohibited abortion in most cases following the overturning of Roe v. Wade in 2022. The law ordered prosecution for anyone administering an abortion or women who had one.

The ballot measure would prohibit the state of Arizona from interfering before the point of fetal viability. Fetal viability is defined in the measure as the point of pregnancy when there is a significant chance of the survival of the fetus outside of the uterus without extraordinary medical measures.

Only 25% of Arizonans favor a ban on abortion, while 60% would likely vote for the ballot measure to pass, Klar’s polling shows. Klar said that Republican candidates have not done well with the abortion issue because they have continued to express support for a federal ban. Trump has said he would not favor a federal ban but believes abortion rights should be handled on a state-by-state basis.

“That could be a big benefit to Democratic candidates,” Klar said.

Conversely, another ballot measure, Proposition 314, would give local law enforcement officers authority to arrest migrants and asylum-seekers who enter Arizona from Mexico without going through an authorized border crossing. She said that the measure could benefit more conservative candidates and bring more conservative voters to the polls.

Border security has become a hot-button issue for Republicans and Democrats in Arizona as well as nationally, but Arizona’s concerns on the issue differ. Trump has continued to push for mass deportations of migrants and asylum-seekers, claiming they commit violent crimes and are taking jobs from Americans.

However, Klar said rather than being so concerned with those who are crossing the southern border, Arizonans focus more on the fentanyl and weapons that are entering the state because of the illegal border crossings.

“The (immigration proposal) is on the ballot to appeal to conservative voters in rural communities who may see this as important,” Klar said.