Harris' border visit isn't just aimed at Arizona. Immigration will also sway voters in states thousands of miles away.

• Kamala Harris in September visited the border for the first time as a 2024 presidential candidate.
• Harris has crafted her messaging on immigration to counter Trump's long-standing border edge.
• But her address in Arizona wasn't solely about winning over voters in the Southwest.

Immigration is one of the defining issues of the 2024 election.

So it was no surprise that Vice President Kamala Harris on Friday visited the US-Mexico border in Arizona, one of the most hotly-contested swing states in the country this year.

Harris' visit to Douglas — a border city of about 16,000 people — was notable because it was her first visit to the southern border since the launch of her Democratic presidential campaign in late July.

Both Harris and former President Donald Trump are fighting to win Arizona by rallying the state's suburban independents and its large Latino population.

Harris is attacking Trump's role in tanking a bipartisan congressional immigration bill that would have overhauled the asylum system and hired more border patrol agents. And Trump wants to tie Harris to the record levels of migrant apprehensions that at various points throughout President Joe Biden's term have severely overwhelmed border patrol agents.

But Harris' remarks in Douglas weren't just aimed at winning Arizona.

She's out to reassure swing voters and independents across the country that she's the candidate who'll deliver on the issue.

"Stopping transnational criminal organizations and strengthening our border is not new to me, and it is a long standing priority of mine," she said during her address in Cochise County, a conservative-leaning jurisdiction where Trump is poised to perform well in November.

However, even in battlegrounds like Michigan, Pennsylvania, and Wisconsin — far from the southern border — voters cite immigration as a top issue. And in rural and exurban areas where Democratic candidates have to cut into GOP margins to win statewide, Harris' messaging will be crucial as she competes alongside Trump to reach the 270-electoral vote threshold for victory.

Border security will be key — but especially among independents

In the latest New York Times/Siena College poll of likely voters in Michigan, immigration was the third most important issue for respondents, with 14% citing it as their top issue. (The economy was the top issue among likely voters overall, with 24% citing it as their most important issue, followed by abortion at 17%.)

Among rural and small town voters, immigration (at 16%) ranked as their second most important issue, with only the economy coming out ahead.

And among independents, immigration and abortion were tied (at 13% each) as their second most important issue. The economy was cited by 25% of likely Michigan independents as their top issue.

The findings are similar in Wisconsin, where the economy is the top issue (28%) among likely voters, followed by abortion (19%) and immigration (12%).

While Harris is poised to perform strongly in the Milwaukee and Detroit metropolitan areas, rural margins in Wisconsin and Michigan will be critical. In these Midwestern states — unlike the South — there remain a sizable contingent of rural voters who continue to vote Democratic on the presidential level.

Harris' remarks on border security were very much aimed at these sort of voters, as many would prefer a bipartisan approach to an immigration overhaul while still enforcing existing laws. And by leaning into her experience as California's attorney general and dealing with the prosecution of drug cartels, she is seeking to turn the page from Biden's handling of the issue, which has been widely panned by voters in recent years.

"I reject the false choice that suggests we must either choose between securing our border or creating a system of immigration that is safe, orderly and humane," Harris said during her Friday speech. "We can and we must do both."

Trump isn't ceding ground on the issue

Trump's 2016 candidacy was driven by his hardline stance on immigration and his 2024 campaign has largely stuck to the same messaging.

The biggest exception is that Trump used Biden's immigration stumbles to build a significant advantage over the president on the issue. But that was before Biden stepped aside as the presumptive nominee and Harris became the Democratic Party's standard-bearer.

Harris has needled Trump on the issue in a way that Biden was not able to do effectively, as the president at the time was also dealing with high apprehensions at the border and migrants being sent by Texas GOP Gov. Greg Abbott to cities like Chicago and New York.

Harris accused Trump on Friday of "playing political games" with border security and emphasized her commitment to tackling fentanyl smuggling and human trafficking should she win the White House.

Trump has retained a significant polling edge on the issue — but that lead has been narrowing.

A newly released NBC News poll showed Trump with a 21-point lead (54% to 33%) over Harris among registered voters regarding border security. It was the former president's biggest advantage on any of the major issues that were polled, including the economy.

However, Trump's lead on immigration issues is down from a 35-point advantage that he previously had over Biden in an NBC News survey conducted in late January.

Trump has been highly critical of Harris' efforts to blast his border security stances. In advance of the vice president's trip to Arizona, he again sought to tie her to Biden.

"She should go back to the White House and tell the president to close the border," the former president said.

With a little over a month before the general election, Trump's advantage appears to be slipping, which could be an enormous boost to Harris in Georgia and North Carolina — where victories by the vice president would very likely send her to the Oval Office.