Trump's Arizona trip keeps immigration front-and-center, as Democrats sharpen border messaging

Former President Donald Trump painted a dark picture on Thursday of what the U.S.-Mexico border would be like if Vice President Kamala Harris were to be elected president.

Trump visited Arizona just hours before Harris was due to accept her party’s presidential nomination on the final night of the Democratic National Convention.

Throughout an hour-long press conference, Trump falsely claimed that Harris supported open border policies, and repeated fake data on how many immigrants entered the U.S. during the Biden-Harris administration.

“If [Harris] has the chance, she will allow more than 100 million illegal aliens into our country,” Trump claimed. “Our country will be overrun, and essentially it won’t be a country.”

Trump also described several grisly crimes allegedly committed by undocumented immigrants.

Fanning voters’ concerns about undocumented immigrants and the Southern border — and then pledging to respond to these fears — are a key piece of the Trump campaign’s strategy.

Harris and Democrats, meanwhile, are still working to develop a unified immigration and border security platform.

That work was on display this week at the Democratic National Convention, where speakers tried to thread a needle between compassion for immigrants, and the tougher border control measures that polls show voters support.

“Let’s be clear: The border is broken,” said House Rep. Tom Suozzi, D-N.Y., on Wednesday night. “This nation, built by immigrants, is a rare and beautiful thing.”

Suozzi is a House freshman who ran for office on a hawkish border platform that helped him flip a Republican-held New York House seat blue.

Migrant crossings at the border skyrocketed last year, overwhelming cities across the country. As state governments rushed to find housing outside of big cities, local leaders quickly realized they lacked the infrastructure to support the incoming immigrants.

At the Chicago convention, Democrats tried to flip the blame on Trump, accusing him of having pressured his Republican allies in Congress to tank a Senate border bill earlier this year, that would have allocated more resources to border security.

“Trump killed that bill,” Sen. Chris Murphy, D-Conn., said Wednesday, a claim that Harris took up in her own acceptance speech later in the week.

Murphy was on the frontlines of the border talks that fell apart, and he blamed Trump for intentionally sabotaging negotiations because the ongoing migrant crisis served Trump’s political goals.

“Hate and division, that’s Trump’s oxygen,” said Murphy..

After the Senate border bill failed, Biden signaled that he would his executive powers to do some of the things the failed bill would have done.

In June, Biden signed an executive action to tighten immigration restrictions, which faced some backlash from progressive immigration advocacy groups.

Biden’s move was intended to send a clear message to border-concerned voters: He would not flinch from taking tough border action.

That harder line was evident in some of the speeches at the Democratic convention.

“When Donald Trump comes down to Texas, stands next to officers in uniforms just like mine. He’s not there to help us,” said Texas county sheriff Javier Salazar Wednesday. [Harris] on the other hand has been fighting border crime for years.”

“When the traffickers didn’t stop, she put them in jail,” he added.

Migrant crossings are down as a result of Biden’s executive action, and the broader impacts of this are already visible on the groud.

Earlier this year, for example, Texas Gov. Greg Abbott was sending buses full of migrants out of his state, in order to redistribute the overwhelming influx of immigrants.

But by July, the Republican governor was no longer sending any migrants north on buses, according to data obtained by NBC News.