In an effort to put pressure on Senate Majority Leader Harry Reid over four controversial recess appointments, Sen. Orrin Hatch (Utah) and 33 other GOP Senators today asked the Nevada Democrat to square his previous opposition with his current stance that the appointments are constitutional.

“We hope you will provide a complete and candid response,” a letter from the lawmakers said.

Reid pioneered the use of keeping the Senate and House from officially recessing by holding short pro forma sessions every three days. Reid used the tactic to prevent President George W. Bush from making recess appointments.

But last month President Barack Obama said the pro forma sessions were a “gimmick” and that the president could use his constitutional recess appointment authority when lawmakers were out of time. Under that justification, he named Richard Cordray to head the Consumer Financial Protection Bureau and filled three vacancies on the National Labor Relations Board, including a Republican spot.

The move outraged Senate Republicans, who called the move unconstitutional because they say the executive branch should not be able to determine when the legislative branch is in session.

The GOP letter asked Reid to explain why he has supported the Obama move, even though he indicated under Bush that recess appointments were not permissible while Congress was holding pro forma sessions.

“This apparent shift in your position raises a number of concerns,” the letter said. “Most specifically, it appears that you believe the importance of preserving Senate’s constitutional role in the nomination and appointment process varies depending on the political party of the President.

“We hope that this is not the case,” the letter continued.

The letter asks Reid to answer the following questions: “Does Reid believe pro forma sessions limit the president’s ability to make recess appointments? Would it have been constitutional for President George W. Bush to make appointments when Reid was using pro forma sessions to deter them? If not, why was it OK for Obama to make his appointments?”

The letter also asks whether the deal to extend the payroll tax break, which was approved in December during a pro forma session, was constitutional, and if it was, whether Reid believes the Senate was unavailable to perform its “advice and consent” in relations to nominations during that time.

Sen. Lamar Alexander (R-Tenn.) also said in a speech on the floor today that the 47 Republican Senators would insist on a full debate on the issue and would file amicus briefs to court cases challenging the appointments.

“This Senate has always been the place — whether it was a Democratic Senate arguing about the appropriateness of President Bush using war powers, this Senate has always been the place that has insisted upon checks and balances and the liberty of the people as guaranteed by those checks and balances,” Alexander said. “The president’s recent actions have shown disregard for possibly the best known and possibly most important role of the Senate, and that is its power of advice and consent of executive and judicial nominations as outlined in Article II, Section 2 of the Constitution.”

Reid has repeatedly said he agreed with Obama’s move. He has said that Republicans left the president no other choice because they held up Cordray’s nomination over their dislike of how the law set up the CFPB, something Democrats argue was unprecedented. Democrats also said that the appointments to the NLRB, also an agency Republicans are not fond of, were needed for the agency to have a quorum and conduct business.

“It’s a constitutional right the president has,” Reid said at a news conference last week. “They were basically giving the president no nominations. For example, they don’t like a law we passed, so they are not going to have any people to fill the [top] position to make that law effective.”