SURPRISED BY THE DEGREE OF SURPRISE…. The day of President Obama’s inauguration, the federal budget deficit left by the Republican administration was $1.3 trillion. After some additional economy-saving measures were added to the mix, the 2009 deficit reached $1.4 trillion. Last year, things improved slightly, and the deficit fell to $1.29 trillion.

Yesterday, the Congressional Budget Office warned lawmakers that the budget picture was poised to get worse again, projecting a $1.5 trillion deficit this year.

Summarizing the thoughts of many, Sen. Mark Kirk (R-Ill.) told Roll Call, “I think everyone is in a collective state of shock right now over the CBO numbers.”

Really? Why is Congress so surprised? Frankly, I’m a little shocked by their collective state of shock.

This really isn’t complicated. The deficit picture was starting to improve, but congressional Republicans insisted that Bush-era tax breaks get extended for another two years. How did Republicans propose paying for these tax cuts? They didn’t — the GOP said the price tag should just be added to the deficit.

And wouldn’t you know it, that means … I hope you’re sitting down … the deficit will go up, just as lawmakers were told it would if they cut taxes without paying for them.

The government’s budget deficit will soar to nearly $1.5 trillion this year, the nonpartisan Congressional Budget Office said Wednesday, an anticipated but politically galvanizing calculation that further intensified the partisan battle over the nation’s fiscal future.

The $1.5 trillion deficit projection is $414 billion higher than its previous estimate, in August, and reflects in part the tax cut deal last month between President Obama and Republicans.

The fact that Congress is surprised only reinforces the fact that Republicans aren’t paying close enough attention to reality. There’s no great mystery here — the deficit is going up because of the new round of tax cuts. That’s what happens when one cuts taxes — less revenue means higher deficits.

If Republicans didn’t want a higher deficit, they shouldn’t have fought so hard to make it worse. They had a choice — expensive tax breaks or deficit reduction. They made their choice, were told what the consequences would be, and are now stunned by the realization that the rules of arithmetic haven’t been suspended by the GOP’s force of will.

It’s unclear to me why Republicans aren’t confronted with hysterical laughter when they claim credibility on fiscal issues. This is a party that inherited a massive surplus a decade ago, when we were actually paying off our debt. The GOP proceeded to squander the surplus, add $5 trillion to the debt in just eight years, and then demand Democrats clean up their mess.

When Dems did just that and the deficit picture started to improve, Republicans then demanded tax breaks that once again made the budget shortfall worse.

Deficit hawks that vote Republican are tragically confused. There’s never been a more fiscally irresponsible political party.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.