HOW NOT TO BE TAKEN SERIOUSLY ON BUDGET ISSUES…. At face value, the pledge from congressional Republicans to slash $100 billion from the federal budget is itself superficial and shallow. It’s not as if GOP leaders identified $100 billion in unnecessary spending and vowed to eliminate it, or identified some specific policy benefit associated with these cuts.

Rather, Republicans picked $100 billion as an arbitrary figure — apparently chosen because it’s a round number — and then started working backwards to reach their capricious goal.

Yesterday, CNN reported on how party leaders intend to reach their target.

Republicans view their midterm electoral victory as a mandate to cut spending, and cutting $100 billion from a $3 trillion federal budget sounds like a reasonable goal.

But GOP leaders say they will focus only on non-security discretionary spending, and won’t slash funding for defense, Social Security or Medicare.

That makes their task a lot harder.

Cutting non-security discretionary funds by $100 billion means a 21% annual reduction in the part of the budget that includes funding for education, health and human services and housing and urban development, among other things, according to the Center on Budget and Policy Priorities, a liberal think tank.

So, let me get this straight. Republicans started by prioritizing deficit reduction over economic growth, itself a ridiculous proposition. GOP leaders then decided, despite their top priority, that they wouldn’t touch the Pentagon budget, Social Security, or Medicare — the three things we happen to spend the most on. They also decided that taxes can’t go up a penny on anyone.

And to top things off, Republicans are demanding $100 billion in spending cuts, mostly to education and health care, in large part because they think the number sounds good.

Remind me, why should anyone take the GOP seriously on budget issues?

The fact that Republican leaders are prepared to leave defense spending intact is especially hard to defend. Indeed, it comes as something of a surprise — in recent months, Republican Sens. Tom Coburn (Okla.), Mark Kirk (Ill.), Rand Paul (Ky.), Pat Toomey (Pa.), Bob Corker (Tenn.), and Johnny Isakson (Ga.) have all said Pentagon spending has to be on the table. Rep. Paul Ryan (R-Wis.), the incoming chairman of the House Budget Committee, has said the same thing. Even Pentagon leaders themselves have said the defense budget is unsustainable.

This shouldn’t even be controversial. Defense spending will top $700 billion in the next fiscal year. For Republicans to insist that we cut spending, but deliberately ignore the largest discretionary portion of the budget, is absurd.

The United States now spends about as much on defense as every other country on the planet combined. Every penny has been deemed entirely necessary by the Republican leadership?

It’s the first hurdle that has to be cleared for the rest of the fiscal discussion to even get underway. Those who claim credibility on the subject, but believe a bloated Pentagon budget is untouchable, shouldn’t even be part of the conversation.

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.