The Senate is no longer attempting to override President Obama's "double veto" on union organizing rules, despite the fact that it may be unconstitutional.

For the first time in history, the president issued an unusual "pocket-and-return" veto on the same Senate bill in order to block the GOP-controlled Congress from overriding his veto and rolling back pro-labor union organization rules. However, legal scholars say the Commander-in-Chief is only allowed to issue either a pocket veto or a return veto. As a result, his use of both veto powers on the same bill may be unconstitutional.

Despite the debate over the constitutionality of Obama's double-veto, the Senate overwhelmingly voted on Tuesday to permanently table Obama's veto message on Tuesday.

Senate Majority Leader Mitch McConnell said he voted to table the override vote because Democrats insisted on a 60-vote, filibuster-proof threshold on a procedural vote. That has never occurred on a veto override in Senate history, said McConnell spokesman Don Stewart.

On the other hand, Iowa Sen. Chuck Grassley, who was one of three Republicans voting to move forward with the override vote, "thought the labor bill deserved debate on its merits, regardless of the controversial way the president handled the veto and the minority party's threat of tying up the Senate floor for several days over the issue," said spokeswoman Jill Gerber, reports USA Today.

"That would have taken us the balance of the week. It was a stalling tactic. There will be other overrides though, I'm sure," Stewart said.

According to Robert Spitzer, an author and political science professor at the State University of New York-Cortland, the bipartisan vote is a sign that the decision was largely procedural.

"This was not an effort to permanently bury Congress' objections to the manner of Obama's veto," said Spitzer, describing Obama's strategy as "a back-door way to expand the veto power contrary to the terms of the Constitution."