Story highlights "It wasn't that Donald Trump won the election, it was that the Democratic Party lost the election," Sanders said

The event was more of a progressive pep rally than a rehash of the 2016 campaign

(CNN) Bernie Sanders criticized Hillary Clinton's 2016 campaign in Boston Friday night at a progressive rally alongside Sen. Elizabeth Warren, saying the Democratic nominee's loss revealed the need for the "fundamental restructuring of the Democratic Party."

The Vermont senator also said some Democrats believe the voters who backed President Donald Trump are racists, xenophobes and "deplorables," a word Clinton famously used.

"I do not agree," he said.

"It wasn't that Donald Trump won the election, it was that the Democratic Party lost the election," Sanders added.

He ran through Democratic losses in recent years -- checking off the Republican-controlled House, Senate, governor's offices and state legislatures -- before saying that Republicans are "a right-wing extremist party who has an agenda that most Americans soundly and roundly disagree with."

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