Minnesota Congressman Collin Peterson is one of just two House Democrats to vote no on ground rules for an impeachment inquiry of President Donald Trump.
The House approved the package on a 232-196 vote, with all Republicans against. New Jersey Rep. Jeff Van Drew was the other Democrat opposed.
Peterson had said in the past that an impeachment proceeding is pointless without bipartisan support, and would only divide the country further.
He added to that Thursday with a statement saying he has "some serious concerns with the way the closed-door depositions were run" and said he is "Skeptical that we will have a process that is open, transparent and fair."
Olson said Peterson's vote on the inquiry is in line with his behavior in the past.
"I think it is traditional and historic in that his way of thinking is that, they are in Congress to get work done and this is a distraction for that," Olson said.
Olson said Peterson has long described himself as a conservation Democrat working against the more progressive Democrats.
"And so I think this is not so much of a political move, but it is in line with his history of bucking his party now and then."
Peterson represents the northwest portion of Minnesota, though his victory margin has declined in recent years in the firmly conservative territory that went strongly for Trump in 2016. He's among more than 60 Democrats nationwide who have already been targeted by Republicans with ads critical of impeachment.