Story highlights Sen. Jeff Merkley says Sanders will "rethink" American politics and the economy

More than 80% of current Democratic senators have endorsed Clinton

Washington (CNN) Jeff Merkley, who on Wednesday became the first U.S. senator to endorse Bernie Sanders, promptly downplayed expectations for the Democratic contender's campaign promises.

"They are a campaign vision," Merkley, an Oregon Democrat, told CNN's Jake Tapper on "The Lead." "You can call them a promise to fight for the direction we need to go."

Merkley was responding to a longstanding criticism from Democrats and others that Sanders' proposals -- including free tuition at public universities and universal health care coverage -- are too "pie in the sky."

The New York Daily News blasted Sanders on its front page declaring him a "fantasist."

But Merkley argued that even presenting the goals he espouses makes them more likely to happen.

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