MCALLEN, Texas (AP) — South Dakota Gov. Kristi Noem's whirlwind tour of the U.S. border with Mexico on Monday was filled with climbing into military vehicles, visiting with troops and positioning herself as tough on an issue that's sure to loom large in 2024 presidential debates.

The Republican governor flew to McAllen, Texas, to check in on the roughly 50 National Guard members who volunteered for a 30-day deployment. She heard how troops have encountered many children crossing and are eager to be stationed where even more people cross the border each night. By the end of the day, she had doubled down on border policy, saying she was considering extending the National Guard's assignment for more months.

"The reality of it is astonishing," Noem told The Associated Press after meeting with the troops. "What our soldiers are seeing is a porous border."

The ambitious governor 's first visit to the border gives her a chance to pick up where former President Donald Trump left off in making hard-line immigration measures a driving force of the Republican Party. Noem eagerly joined the political fight with President Joe Biden after a surge in border crossings, sending the South Dakota Guard members to aid Texas' push to arrest people crossing the border illegally and charge them with state crimes.

"This is a national security threat behind us," Noem said at a news conference near a border wall. "What we see happening behind us is an open border. The drugs that come into South Dakota come over this border."

But the governor has also stepped into a border policy debate that has no easy answers. She described how National Guard members are eager to help with border security, but have also been thrust into an environment where it's difficult to determine why people are crossing. 

Large numbers of migrants have been showing up at the U.S. border with Mexico, with many turning themselves over to U.S. Border Patrol agents in seeking legal asylum status. U.S. officials reported this month that they had encountered 55,805 members of families with children in June, up 25% from the previous month. That figure still remains far below the high of 88,587 in May 2019.

For any Republican eyeing a 2024 presidential bid, a trip to the U.S.-Mexico border may become as necessary as visiting early primary states. Among the governors who have joined Gov. Greg Abbott's initiative, Noem and Florida Gov. Ron DeSantis are the only ones to stage a news conference with the border as a backdrop.

Noem posed for photos with troops stationed on the Rio Grande River, inspected night-vision-enabled military trucks, and munched on burgers with her National Guard escort.

However, Noem's trip comes with its own political baggage: She was  fiercely criticized for accepting $1 million from a Republican donor to fund the deployment. Military experts said it set a troubling precedent that sent a message that military troops could be deployed at the behest of private donors.

But Noem brushed aside those concerns, and instead cast the donation as proof she is fiscally conservative. By accepting the donation, she argued, she was saving taxpayer money. And she was already eager to join the border fight when Tennessee billionaire Willis Johnson called with his $1 million offer — she was just deliberating whether to send police officers or National Guard troops.

Noem said many others have reached out to offer donations to fund the deployment. She said she would evaluate any further offers, but added that she would like to see Texas help fund the deployment if it lasts beyond the initial two months she committed.

Meanwhile, Texas authorities last week began arresting people along the border on trespassing charges. At least 10 people were jailed, but the number of migrant arrests could increase to as many as 100 or 200 per day, according to authorities.

As Noem made her first foray into border policy, she appeared ready to double-down on a tough-on-immigration stance that is sure to be a talking point for years to come.

"A lot of times you can't speak to the reality of something unless you see it," she said.

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