The damage was done last year when Congress voted to spend even more money that we didn't have. The result is that the US debt is now greater than the US Gross Domestic Product.
A Little History
In August of 2011 Congress authorized a debt ceiling increase of between $2.1 and $2.4 trillion. The increase was to happen in up to three steps, and as the ink was drying on the President's signature the administration raised the total debt limit from $14.3 trillion to $15.2 trillion (an increase of around $900 billion) to match ‘cuts’ that were in the bill. The cuts were mostly meaningless, and were spread out over 10 years (while the debt increase was instant) but it gave cover to those who wanted to vote for it. The story was that any increase in debt would be matched with offsetting spending cuts
A Super-Committee was formed to come up with another $1.5 trillion in cuts by December 23. If they failed this would trigger ‘automatic’ cuts of $1.2 trillion beginning in 2013. The final spending reduction was to be added to the $900 billion increase from August. To nobody's surprise the committee was not successful, which means that the total increase is supposed to be limited to $2.1 trillion.
Where we are Today
The Federal Government announced on December 30th that they had had used up all but $100B of the debt ceiling increase. That is $800 billion dollars in just 150 days, which means that the government is borrowing $5.34 billion dollars every day, not the $4 billion that is widely reported.
So the President now wants to increase the total US debt from $15.2 trillion to $16.4 trillion, or 112% of GDP. Congress reserves the right to disapprove of this increase, but the President can veto such an action. The "Resolution of Disapproval" is not as forceful as an actual law and would be something as simple as stating that Congress disapproves of the President's exercise of authority to increase the debt limit. Difficult to say since they voted for it in the first place.
The Republicans, especially in the House where they are all up for election, will probably decide to make a big show and vote against the increase, forcing Obama to nullify the vote with a veto. This is the best political strategy because it gives them cover in November (or in a primary) and allows them to make Obama out to be the bad guy. And since they won't have the votes to override the veto everyone will get the extra money anyway.
You would think that Representatives who voted for the increase in 2011 will have a difficult time voting against it this time. The excuse they might try is that they were made promises that were not kept, which isn't true. They were promised a vote on a balanced budget amendment and that a Super Committee would be put together to find cuts to offset the debt limit increases. Both of these happened. A balanced budget amendment was brought to the floor in November of 2011. It was a bad amendment (see why HERE) but with the exception of a few true conservatives many in Congress voted for it anyway. The Super Committee did not choose their own cuts but, in theory, the offsetting cuts will be made for them.
(Aside - The definition of Irony - Get a promise to vote on a balanced budget amendment by voting for a bill that puts the budget more out of balance.)
The only other excuse I see for those who were in favor of it in 2011 but now want to come out against it is that they didn't really know what was going on the first time. But the "I voted for it before I vote against it" doesn't play well to conservatives, and no congressman wants to admit that they might have made a mistake.
There is one other option. They could do nothing and just hope it passes by without notice. But they should know by now that we are watching.