The Senate voted 51-37 Monday to end debate on the controversial nomination of Keith Harper to be a U.S. representative to the United Nations Human Rights Council.

Citing ethical concerns, most Senate Republicans opposed Harper’s nomination because he was a former fundraiser for President Obama. But Sen. Susan Collins (R-Maine) voted with Democrats.

Sen. John McCain (R-Ariz.) criticized Harper, saying he was the “latest bundler blunder” nominee.

“Mr. Harper is just another example of a campaign bundler wholly unqualified for the position in which he is nominated,” McCain said ahead of the vote. “What [also] concerns me is his character.”

Harper, a member of the Cherokee Nation in Oklahoma, was a top bundler for the Obama’s presidential campaign in 2008 and a member of the administration’s transition team. He would be the first member of a federally recognized tribe to serve in an ambassador role.

McCain said Harper did a disservice to Native Americans when he served as co-counsel in the class-action lawsuit Cobell v. Salazar. The lawsuit resulted in a $3.4 billion settlement and Harper made millions from the deal.

McCain said four Native Americans involved in the lawsuit didn’t want to accept the deal, but Harper and his legal team “bullied” them into it.

“He clearly abused these people’s human rights and now he’s going to be an ambassador on human rights?” McCain said.

The Senate Foreign Relations Committee cleared Harper’s nomination on a party-line vote in February. 

Republicans forced Democrats to vote to end debate before his final confirmation. Last year, Senate Democrats used the “nuclear option” to unilaterally change the filibuster rules so that a simple majority can advance most nominations instead of the previously needed 60 votes.

“This nomination wouldn’t have come to the floor if we still required 60 votes,” McCain said. “This is a deprivation of my right to advise and consent.”

Harper’s final confirmation is expected Tuesday.

— Jasmine Sachar contributed to this article.