Somersworth, New Hampshire (CNN) Former Vice President Joe Biden is more sharply attacking his top rivals as he campaigns in New Hampshire after a poor showing in the Iowa caucuses, singling out Vermont Sen. Bernie Sanders and former South Bend, Indiana, Mayor Pete Buttigieg during a speech on Wednesday.

Biden warned attendees at his event that Sanders would hurt Democrats running in down ballot elections because he is a democratic socialist. And he admonished Buttigieg for what he described as criticism of President Barack Obama's presidency.

Biden's comments were a notable shift in tone for the former vice president, who had a disappointing showing in Iowa behind Buttigieg, Sanders and Massachusetts Sen. Elizabeth Warren. Buttigieg is currently leading the Iowa caucus with 71% of precincts reporting, with Sanders close behind.

"If Sen. Sanders is the nominee for the party, every Democrat in America up and down the ballot, in blue states, red states, purple states, in easy districts and competitive ones, every Democrat will have to carry the label Sen. Sanders has chosen for himself," Biden said at an event in Somersworth, New Hampshire. "He calls him --- and I don't criticize him -- he calls himself a democratic socialist. Well, we're already seeing what Donald Trump is gonna do with that."

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