PHOENIX - President Donald Trump traveled Tuesday to the western state of Arizona, drawing tens of thousands of his supporters and protesters to downtown Phoenix and intense precautions by security forces hoping to prevent violence.

Before the main political event in the Arizona capital, the president headed to a Marine Corps base in Yuma, on the border with Mexico and a center of U.S. Border Patrol operations in the area. Trump's familiar pledge to build a wall along the U.S.-Mexico border to try to thwart illegal immigration will be a primary theme of his remarks late Tuesday.

The interim director of U.S. Immigration and Customs Enforcement, Tom Homan, told reporters aboard Air Force One as the presidential jet headed to Arizona: 'The president's message is that we need a strong border and we need stronger ... enforcement.'

Trump's visit to the Border Patrol base included a scheduled inspection of enforcement aircraft, including a drone and a helicopter, and meetings to evaluate the Border Patrol's operational results, policies and morale 'in the lead-up to fiscal year 2018,' another administration official told reporters.

What U.S. teams guarding the border have done since Trump took office seven months ago 'has worked,' Homan said. 'We need funding to make it permanent. We need to build a wall. A border wall [will be] successful.'

Congress has not yet completed work on a budget for the U.S. government for fiscal 2018, which begins October 1.

FILE - Former Sheriff Joe Arpaio leaves the federal courthouse on July 6, 2017, in Phoenix, Arizona.

Ahead of Trump's arrival, there was speculation he might announce a pardon for Joe Arpaio, the former sheriff of Maricopa County, Arizona, and renowned hard-liner on immigration policies. But that was not to be.

'There will be no discussion of that today at any point, and no action will be taken on that front at any point today,' press secretary Sarah Huckabee Sanders told reporters aboard Air Force One.

Arpaio, 85, was an early, high-profile supporter of Trump's presidential campaign. He recently was convicted of contempt of court for ignoring a judicial order to halt his unilateral anti-immigrant patrols.

The president rejected Phoenix Mayor Greg Stanton's request to postpone or cancel Tuesday's rally. The Democratic official had expressed concern about Trump's recent comments about violent demonstrations in Virginia.

The mayor said Trump's statements doused racial tension with gasoline, and that he feared 'the president may be looking to light a match' in Arizona.

FILE - Protesters march through downtown Phoenix, May 1, 2017. Immigrant and union groups marched in cities across the United States on Monday to mark May Day and protest against President Donald Trump';s efforts to boost deportations.

Supporters of the president began lining up outside the Phoenix Convention Center 18 hours before Trump's address, some coming from other states.

Medics to stand by

Outdoor temperatures were expected to peak above 40 degrees Celsius (104 degrees Fahrenheit) Tuesday. Volunteer medics said they would be downtown to treat possible victims of heat exhaustion or dehydration, and to render first aid if violence should erupt.

Roads were closed to create an open space for large crowds outside the convention center, and local authorities said they would ensure there were no clashes.

Members of a motorcyclists group known as Bikers for Trump planned to ride to the convention center to protect the president's supporters from harassment.

Several local protest groups formed by members of Phoenix's Hispanic, Jewish and Native American communities were joined by some out-of-town protesters - none likely to be more prominent than a 6-meter-tall inflatable chicken with a golden comb fashioned like Trump's hair. Its handlers said the big bird symbolizes the need for transparency in the Trump administration, and a demand for the president to release his personal tax documents.

Other demonstrators were planning to wear purple to honor Heather Heyer, the young woman who was killed in Charlottesville, Virginia, 10 days ago, when a man affiliated with white supremacist groups drove his car into a crowd on the day after a protest march by torch-bearing demonstrators resulted in clashes with other protesters.