FAILING THE TEST OF FISCAL RESPONSIBILITY…. Imagine if, in the midst of a larger discussion about debt reduction, the Democrats’ most powerful leaders drew a line in the sand: no spending cuts. Period. Full stop.

Dems, in this hypothetical, said they agreed with the importance of addressing the problem, but before the debate advanced, they wanted to make one thing clear: spending cuts would be bad for the economy, so Republicans ought to just forget about it. Democrats would compromise, but not on this fundamental point. If we’re going to tackle the problem, they’d say, the exclusive focus would be on receipts, not expenditures.

If Democrats were to take this line, it’s safe to assume they’d be mocked, laughed at, and dismissed as unserious. And yet, Republican leaders are making this precise argument, only from the other direction.

House Speaker John A. Boehner will issue a warning Tuesday to President Obama a day before the president is set to deliver a major speech on the nation’s deficit: Raising taxes is “unacceptable and a nonstarter.”

Mr. Boehner plans to issue the warning in a statement Tuesday afternoon, according to a copy of the statement The Caucus obtained. In it, Mr. Boehner says Republicans are “open to hearing” proposals from Mr. Obama about dealing with Medicare and other entitlements that reduce the nation’s long-term debt.

But he says a proposal by the president that includes tax increases will be treated as evidence that the president is not serious about dealing with the country’s long-term fiscal health.

More specifically, Boehner said in a written statement, “[I]f the President begins the discussion by saying we must increase taxes on the American people — as his budget does — my response will be clear: tax increases are unacceptable and are a nonstarter.”

Let’s briefly note the mathematical basics: to reduce a budget shortfall, the government needs more money coming in, less money going out, or some combination of the two. Up until about 1993, Republicans and Democrats generally agreed on the third option, and would argue about the proportions. (Reagan raised taxes seven of the eight years he was in office, precisely to avoid spiraling deficits.)

Those days are over. We have a $1.5 trillion deficit and a $14 trillion debt, most of which is the result of Republican fiscal irresponsibility. The GOP is desperate, at least if the party’s rhetoric is to be believed, to address this alleged “crisis” of their own making.

But if Democrats recommend any tax increases, on any one, by any amount, at any time, Republicans aren’t even willing to have the conversation. Bringing in even one penny of additional revenue to address the budget gap has been deemed entirely unacceptable.

In terms of “seriousness,” there’s no difference between this approach and the hypothetical I described about taking spending cuts off the table.

For what it’s worth, the American mainstream disagrees with the inflexible GOP line. The most recent Washington Post-ABC News poll asked Americans the best way to reduce the deficit. The Republican mantra — the focus must be on spending cuts, and nothing else — received 31% backing. A combination of cuts and tax increases was preferred by a 64% majority.

Hell, 47% of Republicans believe a combination of spending cuts and tax increases is the way to go.

Something to keep in mind when the right goes apoplectic in response to President Obama’s speech this afternoon.

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.