He said Reid promised as recently as last summer he wouldn't attempt to change the process for confirming appointees. "He may as well just have said, 'If you like the rules of the Senate, you can keep them,'" McConnell said.
Noting that Democrats have periodically talked of changing the rules in recent month, he added, "we're not interested in having a gun put to our head any longer."
It was unclear how quickly Millett might be confirmed.
The clash capped a period of increasing irritation on the part of Democrats.
"They have decided that their base demands a permanent campaign against the president and maximum use of every tool available," Sen. Jeff Merkley, D-Ore., a leading advocate of revamping filibuster rules, said Wednesday of Republicans. He said that consideration "is trumping the appropriate exercise of advice and consent" by GOP senators.
The D.C. Circuit Court is viewed as second only to the Supreme Court in power because it rules on disputes over White House and federal agency actions. The circuit's eight judges are divided evenly between Democratic and Republican presidential appointees.
Senior Democrats wary of future GOP retaliation until recently opposed the move, but growing numbers of them have begun lining up behind Reid's effort.
In addition, two dozen groups, including the AFL-CIO and Sierra Club, wrote lawmakers Wednesday supporting the change, saying that "rampant, ideology-based obstructionism is the new norm in the U.S. Senate."
This summer, Democrats dropped threats to rewrite Senate rules after Republicans agreed to supply enough votes to end filibusters against Obama's nominees to the National Labor Relations Board as well as nominees to head the Environmental Protection Agency, the Labor Department and other agencies.
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