A motorcade carrying U.S. President Donald Trump drives past a U.S.-Mexico border fence as he heads for an inspection of border wall prototypes in San Diego, Calif., on March 13, 2018. (Mandel Ngan/AFP via Getty Images)
US President Donald Trump inspects border wall prototypes in San Diego, California on March 13, 2018. (Mandel Ngan/AFP via Getty Images)
President Donald Trump makes his first trip to California as president. The state is the most populous in the country and a Democratic stronghold. (Mandel Ngan/AFP via Getty Images)
The president has warned there would be "bedlam" without the controversial wall he wants to build on the border with Mexico. (Mandel Ngan/AFP via Getty Images)
Supporters of President Donald Trump display signs during a rally attended by about 500 people in San Diego, Calif., on March 13, 2018, where he was visiting the nearby border wall protoypes. (Bill Wechter/AFP via Getty Images)
Demonstrators place a banner reading "Trump stop massive deportations," during a protest against U.S. President Donald Trump's migration policies on the Mexican side of the U.S.-Mexico border in Tijuana. (Guillermo Arias/AFP via Getty Images)
The president's trip to the Golden State was largely upstaged by his own announcement that he had sacked Secretary of State Rex Tillerson. (Mandel Ngan/AFP via Getty Images)
U.S. President Donald Trump holds up a poster of before and after photos of a segment of the border wall prototypes with Chief Patrol Agent Rodney S. Scott, right, in San Diego, Calif., on March 13, 2018. (Mandel Ngan/AFP via Getty Images)
U.S. President Donald Trump inspects U.S.-Mexico border wall prototypes in San Diego, Calif., on March 13, 2018. (Mandel Ngan/AFP via Getty Images)