Story highlights "What you are seeing is a referendum on Donald Trump," Sanders said

Sanders said Trump campaigned on helping the working class, but in office was delivering for the wealthy

(CNN) Voters' views of President Donald Trump's performance should spell trouble for his party in the midterm elections, Vermont Independent Sen. Bernie Sanders said on CNN's "State of the Union."

"What we're seeing in Alabama, what we're seeing in Virginia, New Jersey and in states all across this country, are large voter turnouts, are people standing up and fighting back and demanding that we have a government that represents all of us, not just the 1%," Sanders told CNN's Jake Tapper in an interview that aired Sunday.

He continued, "If I were the Republicans, I would worry very much about 2018."

Sanders pointed to the recent special election in the heavily Republican state of Alabama, where Democrat Doug Jones defeated Republican Roy Moore. He said Moore was "not a strong candidate," but contended the election was evidence that more people were "catching on" that Trump lied about his campaign promises.

"He ran for president saying that he was going to defend the interests of the working class and the middle class, and it turned out he lied," Sanders said. "What you are seeing is a referendum on Donald Trump about a man who said one thing during the campaign and his actions are very, very different."

Read More