Story highlights Sen. Jeff Merkley is the only sitting senator to endorse Bernie Sanders for president

Oregon's primary is Tuesday

(CNN) Oregon Sen. Jeff Merkley, the only sitting senator to endorse Bernie Sanders for president, said Monday the Vermont senator would "absolutely not" run as an independent if Hillary Clinton is the Democratic nominee.

Merkley was a guest on CNN's "New Day," and responded to a tweet by likely GOP nominee Donald Trump urging Sanders to run as an independent because "the system is rigged against him."

Bernie Sanders is being treated very badly by the Dems. The system is rigged against him. He should run as an independent! Run Bernie, run. — Donald J. Trump (@realDonaldTrump) May 16, 2016

Sanders would "absolutely not" run as an independent, Merkley told host Chris Cuomo, noting that the Vermont senator is mindful of the way the 2000 election played out.

"You know, Bernie went into this and he said, 'There's no way I'll be Ralph Nader.' We're not going to split the party, we're not going to empower the Republicans. He understands the damage that Bush did to this nation, and is not going to allow Trump to follow on and do even more damage," Merkley said.

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