WASHINGTON (Reuters) - Businesses and Senate Republicans forced a courtroom showdown with President Barack Obama on Wednesday, asking a federal appeals court to invalidate his surprise appointments to a labor board in January.

Lawyers with the groups and for Obama's Justice Department argued for more than an hour over whether the president exceeded his authority by filling the vacancies while the Senate was out of town but potentially available to act on them.

The case is a test of the president's ability to appoint people temporarily during a Senate recess, a power that bypasses the Senate's usual ability to block nominees and that dates to the U.S. Constitution of 1787.

Obama on January 4 appointed three members of the National Labor Relations Board and named Richard Cordray to run the new Consumer Financial Protection Bureau.

At the time, the Senate was not officially in recess, meeting every few days for minutes at a time but accomplishing no work and with few senators present.

Cordray's appointment is not at issue in the current case, which arrived at the U.S. Court of Appeals for the District of Columbia Circuit as a dispute between soda bottling company Noel Canning and the labor board.

The three-judge panel asked skeptical questions of all sides, leaving no clear indication which way it would rule when it decides the case in the coming months.

The court could decide it must avoid the issue, leaving it up "to the thrusts and parries of the political branches," said Judge Thomas Griffith.

(Reporting by David Ingram; Editing by Howard Goller and Vicki Allen)