SAN DIEGO - President Donald Trump got his chance Tuesday to inspect prototypes for the "big, beautiful border wall" he wants to build to separate the U.S. from Mexico, saying strengthening the border would help stop "99 percent" of illegal immigration — or, he allowed, "maybe more than that."

The president, making his first trip to California as president, was briefed on eight border wall designs. He said he preferred a fully concrete wall because it was the hardest to climb, but he noted that it needed to be see-through.

President Donald Trump reviews border wall prototy President Donald Trump reviews border wall prototypes, March 13, 2018, in San Diego. President Donald Trump reviews border wall prototypes, March 13, 2018, in San Diego.

Trump said the first things he noticed on the drive to view the prototypes were the patched-up holes in part of the existing fence at the border.

"We have a lousy wall over here now, but at least it stops 90, 95 percent," Trump said. "When we put up the real wall, we're going to stop 99 percent. Maybe more than that."

Trump's visit was greeted with peaceful protests by demonstrators both for and against his planned wall. The trip also came amid an escalating battle between his administration and the liberal state, which has refused to help federal agents detain immigrants who are in the U.S. illegally.

Lauren Rees holds up a sign during a rally against Lauren Rees holds up a sign during a rally against a scheduled visit by President Donald Trump, March 13, 2018, in San Diego. Protesters chanted, “No ban! No wall!” near the San Ysidro border crossing, where tens of thousands of people enter the U.S. daily from Tijuana, Mexico, many on their way to work or school in San Diego. Lauren Rees holds up a sign during a rally against a scheduled visit by President Donald Trump, March 13, 2018, in San Diego. Protesters chanted, “No ban! No wall!” near the San Ysidro border crossing, where tens of thousands of people enter the U.S. daily from Tijuana, Mexico, many on their way to work or school in San Diego.

The president said Tuesday that the state's sanctuary policies "put the entire nation at risk." His Justice Department sued California last week over a trio of the state's immigration laws.

"They're the best friend of the criminal," Trump said. "That's what exactly is happening. The criminals take refuge in these sanctuary cities and it's very dangerous for our police and enforcement folks."

While in California, Trump was also expected to address Marines in San Diego before attending a fundraiser in Los Angeles, where he'll stay overnight.

Demonstrations were held at the San Ysidro port of entry in San Diego, the nation's busiest border crossing, where protesters chanted, "No ban! No wall!" as honking cars and buses cheered them on. Protests were also held on the Mexican side, in Tijuana.



In this April 1, 2017, photo, a man in Nogales, Ar FILE - A man in Nogales, Arizona, talks to relatives standing on the other side of the border fence in Nogales, Mexico, April 1, 2017. Under President Donald Trump's plan, fenced sections of the U.S.-Mexican border would be secured with a wall. FILE - A man in Nogales, Arizona, talks to relatives standing on the other side of the border fence in Nogales, Mexico, April 1, 2017. Under President Donald Trump's plan, fenced sections of the U.S.-Mexican border would be secured with a wall.

At San Ysidro, Jose Gonzalez, 21, stopped to snap a photo of the protesters holding signs, including one that read: "Wall off Putin!" — a reference to Russian President Vladimir Putin, who has a seemingly close relationship with Trump.

"I don't think it's really fair how he has the choice to separate us," said Gonzalez, a dual citizen who lives in Tijuana and crosses the border daily to work at a San Diego ramen restaurant.

A supporter of President Donald Trump walks by dur A supporter of President Donald Trump walks by during a rally for the president's visit, March 13, 2018, in San Diego. Trump on Tuesday inspected prototypes on display in California for his "big, beautiful border wall." A supporter of President Donald Trump walks by during a rally for the president's visit, March 13, 2018, in San Diego. Trump on Tuesday inspected prototypes on display in California for his "big, beautiful border wall."

Army veteran Mark Prieto, 48, shook his head as he walked by the protest.

"People are so narrow-minded," the Riverside firefighter said as the crowd chanted. "Finally we have someone who is putting America first."

His wife, Corina Prieto, a nurse who has extended family in Mexico, agreed. Both voted for Trump.

"I think he is doing a lot of good, like protecting our Border Patrol," she said.

FILE - U.S. Border Patrol officers on horseback wa U.S. Border Patrol officers on horseback watch President Donald Trump review border wall prototypes, March 13, 2018, in San Diego. U.S. Border Patrol officers on horseback watch President Donald Trump review border wall prototypes, March 13, 2018, in San Diego.

Trump was to be briefed on lessons learned from the construction of the prototypes built in San Diego last fall. He was also to meet with border agents and officers to ask what they need, Department of Homeland Security spokesman Jonathan Hoffman said.

San Diego's Republican mayor criticized Trump's planned short visit, saying the president wouldn't get a full picture of the city. Kevin Faulconer said a popular cross-border airport terminal connecting San Diego and Tijuana shows that "building bridges has worked wonders."

WATCH: Border wall

?Faulconer, writing in The San Diego Union-Tribune, also said San Diego police work to protect everyone regardless of immigration status, an apparent dig at Trump's push to target illegal immigration.

Trump tweeted about California's immigration policies as he flew to the state aboard Air Force One:

California’s sanctuary policies are illegal and unconstitutional and put the safety and security of our entire nation at risk. Thousands of dangerous & violent criminal aliens are released as a result of sanctuary policies, set free to prey on innocent Americans. THIS MUST STOP! — Donald J. Trump (@realDonaldTrump) March 13, 2018

This isn't Trump's first visit to the border. He traveled to Laredo — one of Texas' safest cities — weeks after declaring his candidacy in June 2015.

Trump told reporters then that he was putting himself "in great danger" by coming to the border. But, he said, "I have to do it. I love this country."