With a $1.5 trillion deficit and a $14 trillion debt — nearly all of which is the result of GOP policies — Republicans believe it’s time to focus almost exclusively at addressing the budget shortfalls. Arithmetic tells us there are two ways to achieve the goal: the government can bring in more money and put out less. Most Dems, like most Americans in general, prefer to do some of both.

The Republican line isn’t as flexible. They’re desperate to deal with fiscal issues — at least they claim to be — but are equally desperate to make sure the government doesn’t bring in another penny of additional revenue from anyone at any time.

As recently as the Reagan/Bush era, the parties understood that a combination of cuts and tax increases were necessary when the deficit got really big, and the parties would fight over the ratio. That was before the radicalization of the GOP.

For all of Sen. Tom Coburn’s (R-Okla.) bizarre antics, it’s good to see him push back against his own party’s line.

“The fact is we’re at the lowest tax rate this country’s been in a hundred years,” Coburn said in an interview on ABC’s Subway Series with Jonathan Karl. “And nobody believes that we’re going to get a bipartisan agreement without some way to increase revenue for the federal government. We’re also at the lowest level in a long time in terms of revenues coming in.”

Increasing tax revenues, Coburn said, does not mean increasing tax rates. Higher revenues could be accomplished by closing tax loopholes for individuals and/or corporations.

As a policy matter, this is usually where the trouble starts. Those GOP officials who are sure they can just close tax loopholes and bring in bundles of money generally struggle to explain exactly which tax loopholes they’re talking about. (What’s more, for many on the far-right, closing tax loopholes counts as a tax increase, and is therefore considered an ungodly abuse on all that is good and holy.)

But putting that aside, at least Coburn is willing to accept the basic and obvious premise — additional revenue is a necessary element of a fiscally-responsible policy.

It’s hard to overstate how much his party disagrees.

Republicans have latched on to a very good talking point, and it’s been all over the place in the run-up to Tax Day. On April 14, when asked why Republicans wouldn’t consider tax increases as a way to reduce the deficit, Speaker of the House John Boehner explained: “Washington does not have a revenue problem. Washington has a spending problem.” That same day, Majority Leader Eric Cantor got the same question. “The fact [that] I think most Americans get, Washington does not have a revenue problem. It’s got a spending problem.” Also on the same day, speaking to an annual event put on by Grover Norquist’s Americans for Tax Reform, Orrin Hatch completed the loop. “We don’t have a revenue problem,” said Hatch. “We all know we have a spending problem.”

They’re wrong. It’s nice of Coburn to notice.

Postscript: By the way, in the ABC interview, Jonathan Karl appears to have asked Coburn exactly zero questions about his role in the Ensign sex/corruption scandal. Why so much of the media appears willing to give Coburn a pass on this remains unclear.

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.