YUMA, Ariz. >> Fresh off a speech on Afghanistan that moved him in a different direction from many of his core voters, President Donald Trump is highlighting his pledge to combat illegal immigration by visiting a Marine Corps base along the U.S.-Mexico border Tuesday.

Trump also scheduled a nighttime rally in Phoenix, which left local officials concerned that emotions may run hot among those inside and outside of the hall so soon after Trump blamed “both sides” for violence at a rally organized by white supremacists in Charlottesville, Virginia.

Even before the rally began, protesters were engaged in minor scuffles and shouting matches with Trump supporters as hundreds of people lined up to get inside the Phoenix convention center and the temperature soared above 100 degrees. At one point, police officers formed a line in the middle of a street to separate the protesters and Trump supporters. In one exchange, a Trump supporter and protester shoved each other. In another, the two groups shouted at each other before moving on.

Still, one potential flashpoint was extinguished when the White House ruled out a pardon, at least for now, for former Maricopa County Sheriff Joe Arpaio.

Trump told Fox News in a recent interview that he was considering issuing a pardon for Arpaio, who awaits sentencing after his conviction in federal court of disobeying court orders to stop his immigration patrols.

White House press secretary Sarah Huckabee Sanders said a pardon was off the table for the time being.

“There will be no discussion of that today at any point, and no action will be taken on that front at any point today,” Sanders told reporters traveling with Trump.

Trump’s first stop was a Marine Corps base in Yuma that is a hub of operations for the U.S. Border Patrol. Trump inspected equipment used on the southern border, including a drone, helicopter and boat, which were on display in a hangar at the base. At one point Trump was spotted patting the side of the drone.

Trump also shook his head as he was shown a series of everyday objects, such as a fire extinguisher, that had been refashioned to secretly transport drugs across the border. After the tour, Trump spent about 20 minutes greeting service members in the grueling, 106-degree heat, signing caps with his “Make America Great Again” campaign slogan and posing for selfies on the tarmac just steps from Air Force One.

Administration officials briefing reporters on the trip said the area had seen a 46 percent drop in apprehensions of people attempting to illegally enter the U.S. between Jan. 1 and July 31, compared with the same period in 2016. None of the officials would agree to be identified by name.

In fact, immigrant traffic around Yuma has dramatically slowed over the past dozen years. Once a hotbed for illegal immigration, the Border Patrol sector covering Yuma now ranks among the lowest in the Southwest for apprehensions and drug seizures.

There were some 138,000 apprehensions in 2005. The number had dropped to 14,000 by last year.

Trump is trying to shift the focus to his core campaign theme of getting tough on immigration after rankling some of his most loyal supporters with his decision, announced Monday, to maintain to a U.S. military presence in Afghanistan. They are also unhappy about the recent ouster of conservative Steve Bannon as White House chief strategist.

Bannon had made it his mission to remind Trump of what his most fervent supporters want from his presidency, and some conservative strategists have openly worried that without Bannon around, Trump will be too influenced by establishment Republicans on issues such as Afghanistan policy.

Democratic leaders and other Trump opponents planned protests and marches outside the Phoenix convention center to criticize the president’s immigration policies and his comments about Charlottesville. Phoenix Mayor Greg Stanton had asked Trump to postpone the rally to allow time for national healing after one woman was killed during the clashes in Charlottesville.

Gov. Doug Ducey, a Trump supporter, greeted Trump upon his arrival in Phoenix, but will not attend the rally to focus on safety needs, his spokesman said.

Vice President Mike Pence, asked about the rally by Fox News Channel today, said Trump will be “completely focused” on his agenda for the country.

“He’s also going to call on the Congress to get ready to come back when they arrive on Sept. 5th and go straight to work to make America safe again, make America prosperous again, and in his words, to make America great again,” said Pence. He was flying separately to Phoenix to introduce Trump at the rally.

Neither of Arizona’s two Republican senators planned to appear with Trump.

Republican Sen. Jeff Flake, a conservative, has been a frequent target of Trump’s wrath. The president tweeted last week: “Great to see that Dr. Kelli Ward is running against Flake Jeff Flake, who is WEAK on borders, crime and a non-factor in Senate. He’s toxic!” Flake has been on tour promoting his book that says the Republican Party’s embrace of Trump has left conservatism withering.

Ward planned to attend Trump’s rally, sparking talk that the president could take the politically extraordinary step of endorsing her from the stage over an incumbent Republican senator.

In a modest but telling swipe at Ward and, by extension, at Trump, the Senate Leadership Fund, a political committee closely aligned with Senate Majority Leader Mitch McConnell of Kentucky, is spending $10,000 on digital ads that say of her, “Not conservative, just crazy ideas.”

Arizona’s other senator, John McCain, is undergoing treatment for an aggressive form of brain cancer. Trump has been critical of McCain for voting against a Republican health care bill.