Donald Trump leads the crowded GOP presidential field by double digits in the final days leading up to New Hampshire’s primary Tuesday, according to the latest Monmouth University Poll released on Sunday. Mr. Trump, a billionaire businessman, earns 30% support from voters likely to participate in Tuesday’s primary, with the next four candidates clustered within two percentage points but far behind Mr. Trump. The poll was taken before Saturday night’s Republican debate. With 14% support from likely voters, Ohio Gov. John Kasich has a narrow lead over Florida Sen. Marco Rubio and former Florida Gov. Jeb Bush, who are tied at 13%, and Texas Sen. Ted Cruz at 12%. The four are within the margin of error of each other.