Anti-Trump protesters stamp on a 'Make America Great Again' caps outside the Anaheim Convention Center after a rally for Republican presidential candidate Donald Trump on May 25, 2016 in Anaheim, California.   
Police were on high alert one day after violence marred a Trump rally in the southwestern state of New Mexico, where anti-Trump protesters hurled rocks and police fired smoke grenades in efforts to rein in the chaos. Dozens of security personnel including police on horseback maintained control in Anaheim, although some skirmishes broke out between Trump opponents and his backers as protesters chanted expletives about the brash billionaire. At least two arrests were made. / AFP / Mark Ralston        (Photo credit should read MARK RALSTON/AFP/Getty Images)