U.S. Sen. Angus King, I-Maine, will oppose the president’s nominee to serve as attorney general.

The Senate Judiciary Committee approved William Barr’s nomination last week along party lines. The Senate is widely expected to confirm the nominee in a vote later this week. King, an independent who caucuses with Democrats, said he attended part of the committee hearing and met with Barr individually to ask questions.

“I do not cast this vote lightly; while there are any number of critical policy areas where Mr. Barr and I have serious differences, he is clearly a knowledgeable nominee who has a deep respect for the Department of Justice,” King said. “I imagine that, under typical circumstances, Mr. Barr would meet my standard that the President should be able to appoint his or her chosen leaders to federal departments, provided that they are not grossly unqualified and do not stand in opposition to the department’s mission. However, I do not consider the present moment to be ‘typical circumstances,’ and two of the nominee’s key positions are so concerning to me as to require a ‘no’ vote.”

Those two issues, King said, are Barr’s expansive views of executive power and his unwillingness to promise to make the special counsel’s findings public.

U.S. Sen. Susan Collins, a Republican from Maine, has not said publicly how she will vote.