It was the first time the White House and congressional Republicans failed to rewrite or overturn environmental regulations put into place by the previous administration. That regulatory rollback, until Wednesday, united the party.
The Bureau of Land Management rule, put into place in November, has been in Republican crosshairs for months. The House has voted to eliminate the rule through the Congressional Review Act, a law that lets Congress unwind some recent regulations.
The Senate was expected to follow suit and deliver a win not just for Republican leadership and the administration, but also for their allies in the oil and gas industry. Instead, Mr. McCain and two fellow Republicans -- Sens. Lindsey Graham of South Carolina and Susan M. Collins of Maine -- joined all 48 Democrats in voting against the measure, leading to its defeat in a 51-49 vote.