Before last night, much of the mainstream media had barely noticed that President Obama’s $4 trillion debt reduction plan was bunk. Sure, The Post’s Glenn Kessler had previously said, “The repeated claim that Obama’s budget reduces the deficit by $4 trillion is simply not accurate,” and he debunked it again last night. However, where were the hordes of media fact-checkers? Where were the pundits enraged about all the “lying” and economic flimflam in the campaign? It seems that Mitt Romney’s performance essentially required them to own up to the truth: Yeah, it’s pretty much nonsense.

NBC had this reaction:

ABC told us: “The first $1 trillion in cuts are already on the books. As he noted in his speech, the president negotiated them with Congress last summer. More cuts are banked by letting the Bush tax cuts expire (the top marginal rate would return to 39.5 percent from 35 percent) and closing a number of arcane loopholes, all of which, in theory, would have a multiplier effect as the resulting interest payments on the national debt would be lessened. Then there’s the issue of military spending. The Congressional Budget Office has already worked nearly a trillion dollars of war expenses into its long-term deficit projections. President Obama, by ending the war in Iraq and winding combat operations in Afghanistan (by 2014), is subtracting that as-yet-unspent money from the future debt load.”

The Associated Press concurred:

In promising $4 trillion, Obama is already banking more than $2 billion from legislation enacted along with Republicans last year that cut agency operating budgets and capped them for 10 years. He also claims more than $800 billion in war savings that would occur anyway. And he uses creative bookkeeping to hide spending on Medicare reimbursements to doctors. Take those “cuts” away and Obama’s $2.50/$1 ratio of spending cuts to tax increases shifts significantly more in the direction of tax increases.

Obama’s February budget offered proposals that would cut deficits over the coming decade by $2 trillion instead of $4 trillion. Of that deficit reduction, tax increases accounted for $1.6 trillion. He promises relatively small spending cuts of $597 billion from big federal benefit programs like Medicare and Medicaid. He also proposed higher spending on infrastructure projects.

So where have all the media been while the president was running around the country peddling this bogus plan? They essentially ignored it, preferring to misrepresent Romney’s tax plan instead.

And speaking of which, the media have spent a lot of time trying to attack Romney’s tax plan using the two main arguments (both of which Obama tried last night): It is a tax cut of $5 trillion, and you can’t keep progressivity and revenue-neutrality. These were repeated endlessly by virtually every mainstream outlet and liberal pundit. Both, as we saw last night, just aren’t so. Obama was plainly baffled and continued to reiterate the spin long after Romney had explained why it wasn’t so.

Romney replied to Obama’s attack like this:

So if the tax plan he described were a tax plan I was asked to support, I’d say absolutely not. I’m not looking for a $5 trillion tax cut. What I’ve said is I won’t put in place a tax cut that adds to the deficit. That’s part one. So there’s no economist that can say Mitt Romney’s tax plan adds $5 trillion if I say I will not add to the deficit with my tax plan.

Number two, I will not reduce the share paid by high-income individuals. I know that you and your running mate keep saying that and I know it’s a popular thing to say with a lot of people, but it’s just not the case. Look, I’ve got five boys. I’m used to people saying something that’s not always true, but just keep on repeating it and ultimately hoping I’ll believe it. But that — that is not the case. All right? I will not reduce the taxes paid by high-income Americans.

Obama repeated the talking points later and Romney again responded, “I want to bring down the tax burden on middle-income families. And I’m going to work together with Congress to say, okay, what are the various ways we could bring down deductions, for instance? One way, for instance, would be to have a single number. Make up a number — 25,000, 50,000 dollars. Anybody can have deductions up to that amount. And then that number disappears for high-income people. That’s one way one could do it. One could follow Bowles-Simpson as a model and take deduction by deduction and make differences that way. There are alternatives to accomplish the objective I have, which is to bring down rates, broaden the base, simplify the code and create incentives for growth.”

One more time, Obama clung to his attack lines, and once more Romney patiently explained: “I think first of all, let me — let me repeat — let me repeat what I said. I’m not in favor of a $5 trillion tax cut. That’s not my plan. My plan is not to put in place any tax cut that will add to the deficit. That’s point one. So you may keep referring to it as a $5 trillion tax cut, but that’s not my plan.”

The now infamous Tax Policy Center claimed it was “impossible” to accomplish Romney’s aims; last night he explained why it isn’t. The Hill reported (and the Romney campaign eagerly circulated it to the media):

The Tax Foundation on Wednesday became just the latest analyst to take a whack at a think tank study questioning the math behind Mitt Romney’s tax plan.

In a new study, the foundation said that the Tax Policy Center study — which President Obama’s campaign has been citing for weeks — did not account enough for the economic growth that the GOP presidential nominee would spur with his plan.

Why was Obama so stumped last night? Apparently he and his aides inside the liberal media cocoon never really understood what Romney was saying, or they chose to mischaracterize it. When splashed with cold water (facts), Obama — not to mention his media cohorts — was dumbstruck. At one point the president even suggested Romney had changed his plan! No, Obama just never got it.

This morning two Romney aides confirmed to me that Romney was showing how his plan could be implemented. One told me that Romney was “explaining one way the plan could be implemented, [but] there are a range of possibilities.” Another told me, “There are lots of ways to implement [Romney’s tax principles]. Last night the governor talked about two. One was a dollar cap on itemized deductions and another would be a 1986-style tax reform.”

So here we have two plans. The president’s $4 trillion debt plan was phony, yet the public probably never heard that until last night. Romney has a viable (you can disagree on the choices and priorities, of course) tax plan, which the public heard about only in a grossly distorted form before last night.

In both cases the Obama team wasn’t being straight with the public; in both cases the media went along until the debate exposed Obama’s untruths. You can understand why conservatives think the media have been in the tank for Obama and why Romney has to break through the media filter to win this.