Story highlights "I'm ready to say that Elizabeth Warren would make a great vice president," he said

"We have our nominee. I want to help her be successful," Merkley said

Washington (CNN) Oregon Sen. Jeff Merkley is "supporting" Hillary Clinton for president but stopped short of saying he endorses the presumptive Democratic nominee.

Merkley was the only Senator to endorse Vermont Sen. Bernie Sanders for president.

"Sen. Elizabeth Warren, the president and the vice president all endorse Hillary Clinton. Are you ready to endorse her as well," CNN's Kate Bolduan asked Merkley Friday.

"Certainly, I'm going to support our nominee and our nominee is Secretary Clinton, but what I really want to see is success in November," he said on CNN's "At This Hour with John Berman and Kate Bolduan."

"This is the first time I think that we've heard you say that you're going to support the nominee and acknowledge that the nominee is Hillary Clinton. Is this an endorsement of some sort," Bolduan asked.

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