Kamala Harris to criticize Trump in her 1st visit to border in more than 3 years

Vice President Kamala Harris will visit the U.S.-Mexico border on Friday -- her first trip there in more than three years -- to call for tougher security measures and attack former President Donald Trump on an issue that has plagued her, a senior campaign official said.

Harris plans to deliver remarks in Douglas, Arizona, a border town in the critical battleground state, where she will continue to criticize Trump for his role earlier this year in tanking a bipartisan bill that was the result of months of negotiations.

"The American people deserve a president who cares more about border security than playing political games," Harris plans to say, according to the senior official, who was granted anonymity to discuss a speech the vice president has yet to deliver.

She will take a strong line in her remarks Friday and make the case that "American sovereignty requires setting rules at the border and enforcing them," the senior official previewed.

As part of her trip, Harris will also meet with border patrol agents, the senior official said, and tout the pay raises the Biden administration gave agents and argue they "need more resources to do their jobs to keep America safe."

Harris' trip comes as immigration is a top issue for many voters ahead of the election. A recent ABC News/Ipsos poll found that 70% viewed immigration at the southern border as an "important" issue for them, and Trump led Harris by 10 points on who voters thought was best suited to handle it.

In 2021, President Joe Biden tasked Harris with the likely doomed-from-the-start assignment of solving the root causes of migration amid surges of migrants arriving at the southern border. Republicans have used this to label Harris the "border czar" though her task did involve U.S. policy at the border itself.

The last time Harris made a trip to the border was in June 2021. Her infrequent visits have also been another source attacks from her opponents.

The senior official said the campaign hopes Harris's trip to the border will help close the gap between Trump on the issue.

Trump held what amounted to a preemptive attack at a news conference in New York on Thursday.

"She should save her airfare," Trump said. "She should go back to the White House and tell the president to close the border. He can do it with the signing of a - of a - just a signature on a piece of paper to the border control; instead, she's going there to try to convince people she wasn't as bad as everybody knows she was."

Harris' campaign is is releasing a new ad on Friday tied to her trip to the border. The 30-second ad, titled "Never Backed Down," highlights Harris' work as a prosecutor.

"She put cartel members and drug traffickers behind bars, and she will secure our border," a narrator says in the ad. The ad says Harris' plans for the border include hiring more law enforcement agents, boosting technology and to "stop fentanyl smuggling and human trafficking."

In her remarks at the border, Harris will say tackling fentanyl will be "a top priority" for her as president and will propose installing new fentanyl detection machines at the border, a senior campaign official said. She will also continue to call on China to quash Chinese companies' manufacturing of fentanyl precursor chemicals, the official added.

"We need a leader with a real plan to fix the border and that's Kamala Harris," the narrator says at the end of the ad.

ABC News' Kelsey Walsh contributed to this report.