The House easily defeated a Balanced Budget Amendment to the Constitution this afternoon, despite overwhelming support from Republican lawmakers. All told, 98.3% of the House GOP caucus today voted to approve the measure.

But 98.3% isn’t 100%. Four Republicans broke ranks — more than in the 1995 vote — and the one that’s likely to get the most attention is House Budget Committee Chairman Paul Ryan (R-Wis.), who, as you may have noticed, spends quite a bit of time talking about the debt crisis.

So, what happened? Ryan has not yet issued a statement on his vote, but I have a hunch I know why he opposed the amendment: it would have made his own budget plan unconstitutional.

Republicans generally don’t like to talk about this, but the Ryan budget plan, if approved, would add $6 trillion in new debt over the next 10 years, caused almost entirely by Ryan’s massive tax cuts for the wealthy. A constitutional requirement mandating balanced budget would make the Ryan plan literally, legally unacceptable.

And that leads to a very different question. In April, 235 Republicans voted for the Ryan budget plan (which, among other things, eliminated Medicare). Today, 236 Republicans voted for the Balanced Budget Amendment. After going through the roll calls, there are 231 GOP House members who voted for the right-wing budget and voted for the constitutional amendment that would have been the right-wing budget impermissible.

I consider Paul Ryan to be a strange and radical policymaker, but on this, at least he’s consistent. If our discourse made more sense, those 231 House Republican lawmakers would be asked to explain themselves.

Postscript: By the way, remember Reagan’s tax cuts and defense build-up in the early 1980s? The agenda that Republicans believed won the Cold War and saved civilization as we know it? It, too, would have been impermissible under a Balanced Budget Amendment. It’s another question for those GOP lawmakers who voted for the BBA today: why would you want to make the Reagan agenda impossible?

Update: I may have given Ryan too much credit for consistency. He told reporters after the vote that the amendment wasn’t quite right-wing enough for him, since it might lead future Congresses to raise taxes to balance the budget — a scenario Ryan considers unacceptable under any circumstances. The Budget Committee chairman can be surprisingly nutty at times.

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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.