Ohio Sen. Rob Portman became the latest Republican senator to call on Donald Trump to quit the race. “While I continue to respect those who still support Donald Trump, I can no longer support him,” Mr. Portman said in a statement. “I continue to believe our country cannot afford a Hillary Clinton presidency. I will be voting for Mike Pence for president.” Mr. Portman becomes the latest in a flood of Republicans to have abandoned the party’s presidential nominee Saturday, a day after a 2005 recording emerged of Mr. Trump making lewd and degrading comments about women.