WASHINGTON, D.C. -- Oregon Senator Jeff Merkley isn’t exactly thrilled about watching Donald Trump become the nation’s 45th president on Friday, but he vowed to work with the Trump administration where they can find common ground.

“I will be there to honor the peaceful transfer of power. But don’t doubt for a second that I won’t fight tooth and nail against the policies of this administration that are designed to hurt working America,” Merkley said in an interview.

Merkley spoke with KGW from his senate office during a lull in a busy day of confirmation hearings. Oregon’s junior senator heard testimony from two of Trump’s nominees on Wednesday: Gov. Nikki Haley for U.N. ambassador and Scott Pruitt for EPA administrator.

“I probably disagree with her on a whole host of policies but I think she’s one of the better nominees that President-Elect Trump has put forward,” Merkley said of Haley.

Full interview: Sen. Jeff Merkley on Trump inauguration

He was less kind when talking about Pruitt.

“That’s the opposite end of the spectrum,” Merkley said. “Scott Pruitt has used his office as the Attorney General in Oklahoma as an extension of the energy industry.”

Merkley said Trump’s cabinet picks overall indicate the president-elect isn’t serious about his promises for fighting for middle class Americans. That’s why he’s not optimistic about Trump’s policies when he takes office.

“I’m not going to feel good. I think there is a huge shadow over the incoming administration. The more we know the darker that cloud becomes,” he said.

“If the administration recognizes that there is no mandate in America for their policies and approaches the policy conversation in a humble way – that is willingness to work together, not have it all just be on one side in a way that alienates the other side – we have the possibility of getting some things done,” Merkley added. “I’m not terribly optimistic about that, but that’s certainly the opportunity I’m going to be looking for.”