OTTAWA -- Sen. John Wallace is resigning from the Conservative caucus, citing "irreconcilable differences" between himself and his party over the role of the upper chamber -- which he feels should be non-partisan.

Wallace said his decision had been some time coming, as he reflected on the constitutional duties of senators to review, critique and amend legislation. It struck him that since he was appointed in 2009, the Senate had dealt with 164 bills, but only amended two.

The former Irving Oil lawyer said changes need to happen and being an Independent will allow him to speak to that.

"For it to have the credibility in the eyes of the public and that it's not there to simply rubber-stamp the political will of the parties, partisanship has to be removed as much as it can be from the Senate," Wallace said in an interview.

He said that there were differences of opinion with Conservative Sen. Leader Claude Carignan and other senators on what their role should be, as well as other issues.

He said he was particularly dismayed with how the suspensions of four senators were handled in 2013 and also how former prime minister Stephen Harper left 22 Senate seats empty.

All senators have been reflecting on their roles as the new Liberal government comes to power without a Senate caucus and with a campaign promise to appoint senators on a non-partisan, merit-based basis.

Wallace said he's encouraged by the proposals put forward by Prime Minister Justin Trudeau and the fact that fellow New Brunswicker Dominic LeBlanc, the Liberal House leader, will be acting as a liaison with the Senate.

"What you end up with is a Senate that is not dependent upon trying to balance their commitments, the responsibilities they have to the Senate institution and the commitment that we each feel we have to a political caucus," Wallace said.

"Trying to find the balance between those two at times is impossible."

With Wallace's new status, there are now 46 Conservatives, 29 independent Liberals, eight Independents, and 22 vacancies in the Senate.

His announcement comes a day before the resumption of Sen. Mike Duffy's trial, which has heard details of how Conservative senators took marching orders from the Prime Minister's Office to help quell a spending scandal.