Hillary Clinton's advantage was sealed on Tuesday night by exceptionally strong support from blacks, Hispanics, women and voters over the age of 30, NBC News exit polls found.
But she's shown weaknesses with key groups of voters that she will need to win the presidency in November if she is the nominee.
One of those weak points is her lack of support among white men. Those votes went to her rival Bernie Sanders, who gained 55 percent of their votes, according to the exit polls.
And Clinton failed to engage the votes of those 17 to 29 years of age, with Sanders grabbing eight in 10 of their votes in Iowa, New Hampshire and Nevada, and then 54 percent in South Carolina.