Ron Johnson is not a familiar name to most Americans who are pondering the politics of the “fiscal cliff.” But Johnson’s reaction to the 2012 election results will tell folks everything they need to know about the challenge rational Democrats will face when it comes to negotiations with not-so-rational Republicans.

A senator from Wisconsin who announced his candidacy at a Tea Party rally and was elected—with help from a family fortune, Karl Rove and the US Chamber of Commerce’s political operations—Johnson has been a congressional absolutist when it comes to budget issues. He embraces House Budget Committee chairman Paul Ryan’s austerity agenda, perhaps even more than Ryan does himself. And he swears, against all economic evidence to the contrary, and against all political evidence of opposition on the part of the American people, that there is only one way to address the challenges facing America: tax cuts for rich people like him and benefit cuts for everyone else.

Johnson would be a laughable figure—he’s the subject of a Wisconsin website titled “Our Dumb Senator”—were it not for the fact that he takes himself so seriously. And he is part of a Republican caucus in the Senate that, like the parallel Republican caucus in the House, must deal with its Ron Johnsons before it can function legislatively.

Where Johnson and other absolutists like him take themselves most seriously is it comes to fiscal concerns.

So seriously, in fact, that Johnson greeted the news of Barack Obama’s re-election by suggesting that the president—whose ideas were backed by Nobel Prize–winning economists such as Michael Spence—won by securing the votes of “people who don’t fully understand the very ugly math we are facing in this country.”

That sparked a flurry of national commentary on Johnson in particular and the over-the-cliff wing of the GOP in general.

But the even more telling comment from Johnson was his response to the election of Congresswoman Tammy Baldwin, D-Madison, to the US Senate by telling the Associated Press: “Hopefully I can sit down and lay out for her my best understanding of the federal budget because they’re simply the facts. Hopefully she’ll agree with what the facts are and work toward common sense solutions.”

In other words, Johnson wants Baldwin to agree with him.

Unfortunately for Johnson—if not America—what he refers to as “facts” are actually his “opinions”—that the United States cannot afford to maintain Social Security, Medicare and Medicaid because it needs to maintain tax breaks for rich guys like, um, Ron Johnson.

Baldwin is too smart and too experienced to believe what Johnson does.

Yet, she was gracious in her response to his “mansplaining” of how to do math.

“I was a double major in college in mathematics and political science, and I served for six years on the House Budget Committee in my first six years in the House,” Baldwin explained, when asked by the Huffington Post about her colleague’s greeting. “And I am very confident that when proposals come before the US Senate, I will be able to evaluate them as to how they benefit or harm middle-class Wisconsinites. A yardstick of ‘does it create jobs,’ ‘does it lower the deficit’ and ‘does it help grow the middle class’ is an important one. I’m quite confident that I have those abilities.”

Baldwin is dramatically better prepared to be a useful contributor to budget debates than Johnson. She knows her way around Washington, and she has been a thoughtful critic of wasteful spending for years. The difference is that she is far more willing than Johnson to hold wealthy and powerful interests to account. Indeed, as a member of the Congressional Progressive Caucus, she and her colleagues have over the years proposed plans that balance the budget more quickly and responsibly than the proposals made by Ryan.

If Ron Johnson really was interested in facts, he would seek a briefing from Tammy Baldwin.

Johnson isn’t the only legislator that could learn a thing or two about the so-called “fiscal cliff.” Check out the latest from TomDispatch, “CliffsNotes for Washington.”