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President Barack Obama's appointments to two key agencies during the Senate's year-end break ensures that GOP senators will return to work Monday in an angry and fighting mood.

Less clear is what those furious Republicans will do to retaliate against Obama's "bring it on" end run around the Senate's role in confirming nominees to major jobs.

While Republicans contemplate their next step, recess appointee Richard Cordray is running a new Consumer Financial Protection Bureau, and the National Labor Relations Board, with three temporary members, is now at full strength with a Democratic majority.

Obama left more than70 other nominees in limbo, well aware that Republicans could use Senate rules to block some or all of them.

The White House justified the appointments on grounds that Republicans were holding up the nominations to paralyze the two agencies. The consumer protection agency was established under the 2010 Wall Street reform law, which requires the bureau to have a director in order to begin policing financial products such as mortgages, checking accounts, credit cards and payday loans.

The Supreme Court has ruled that the five-member NLRB must have a three-member quorum to issue regulations or decide major cases in union-employer disputes.

Several agencies contacted by The Associated Press, including banking regulators, said they were conducting their normal business despite vacancies at the top. In some cases, nominees are serving in acting capacities.

The Federal Deposit Insurance Corp., at full strength, has five board members. The regulation of failed banks "is unaffected," said spokesman Andrew Gray. "The three-member board has been able to make decisions without a problem." Cordray's appointment gives it a fourth member.

The Comptroller of the Currency, run by an acting chief, has kept up its regular examinations of banks. The Federal Trade Commission, operating with four board members instead of five, has had no difficulties. "This agency is not a partisan combat agency," said spokesman Peter Kaplan. "Almost all the votes are unanimous and consensus driven."

Republicans have pledged retaliation for Obama's recess appointments, but haven't indicated what it might be.

"The Senate will need to take action to check and balance President Obama's blatant attempt to circumvent the Senate and the Constitution, a claim of presidential power that the Bush Administration refused to make," said Sen. Charles Grassley, an Iowa Republican who is his party's top member on the Senate Judiciary Committee.

Grassley wouldn't go further, and Senate Republican leader Mitch McConnell of Kentucky hasn't tipped his hand after charging that Obama had "arrogantly circumvented the American people." Before the Senate left for its break in December, McConnell blocked Senate approval of more than 60 pending nominees because Obama wouldn't commit to making no recess appointments.

Republicans have to consider whether their actions, especially any decision to block all nominees, might play into Obama's hands.

Obama has adopted an election-year theme of "we can't wait" for Republicans to act on nominations and major proposals like his latest jobs plan. Republicans have to consider how their argument that the president is violating Constitutional checks and balances plays against Obama's stump speeches characterizing them as obstructionists.

Senate historian Donald Ritchie said the minority party has retaliated in the past for recess appointments by holding up specific nominees. "I'm not aware of any situations where no nominations were accepted," he said. The normal practice is for the two party leaders to negotiate which nominations get votes.

During the break, Republicans forced the Senate to convene for usually less than a minute once every few days to argue that there was no recess and that Obama therefore couldn't bypass the Senate's authority to confirm top officials. The administration said this was a sham, and has released a Justice Department opinion backing up the legality of the appointments.

Obama considers the new Consumer Financial Protection Bureau a signature achievement of his first term. Republicans have been vehemently opposed to the bureau's setup. They argued the agency needed a bipartisan board instead of a director and should have to justify its budget to Congress instead of drawing its funding from the independent Federal Reserve.

Cordray is expected to get several sharp questions from Republicans when he testifies Tuesday before a House Oversight and Government Reform panel.

The NLRB has been a target of Republicans and business groups. Last year, the agency accused Boeing of illegally retaliating against union workers who had struck its plants in Washington state by opening a new production line at its non-union plant in South Carolina. Boeing denied the charge and the case has since been settled, but Republican anger over it and a string of union-friendly decisions from the board last year hasn't abated.