“Not sure I understand @ezraklein’s view that Paul Ryan ‘unintentionally’ wrote a budget that soaks the poor,” tweeted Matt Yglesias earlier today. And he’s right, Wonkbook was a bit unclear. So I’ll explain.

Go back to Paul Ryan’s original ‘Roadmap.’ It began with a health-care section, the purpose of which was to ensure “universal access to affordable health insurance.” The core of the plan was a restructuring of the tax code so the regressive tax credit for employer-based health insurance became a progressive refundable tax credit for all Americans. There’s also a section trying to modernize and improve the federal government’s suite of job training initiatives.

Or go back to Mitt Romney’s governorship of Massachusetts. His signature accomplishment was a health-care bill that spent lots of money to insure low-income Bay Staters.

Fast forward a few years and both men are, in different ways, leaders of the Republican Party who are responsible for putting out comprehensive budgets. And both of their budgets now work the same way: They dramatically cut health-care subsidies and income supports for the poor to fund tax cuts, higher defense spending and substantial deficit reduction, and they do nothing to expand or strengthen the safety net.

One explanation is that Romney and Ryan changed, or are showing a truer version of themselves now. Another argument — and I think this is clearly part of the story — is that conditions changed, and it’s simply harder now for a Republican to propose expanding access to health insurance. But that doesn't explain why they’ve embraced such deep cuts to food stamps — which George W. Bush expanded — and housing subsidies, to name just a few.

In a broad sense, what their evolution suggests is that there are structural factors in the Republican Party that are pushing leaders toward making these kinds of budget decisions. The fact that Newt Gingrich — who also supported various universal health-care plans over the past decade — and Rick Santorum have released similar fiscal proposals, albeit with more tax cuts and, in Santorum’s case, more draconian spending cuts, is more evidence that there’s something structural going on here.

Or, to put it a bit more simply, in 2000, Bush ran for president criticizing those who would “balance the budget on the backs of the poor.” In 2005, Mitt Romney, preparing to run for president as a Republican, passed a universal health-care plan. Around the same time, Paul Ryan was releasing ambitious budgets that paid at least some attention to improving matters for the poorest Americans.

Today, the Republican Party is in a different place, and my theory is that it’s because they’ve committed themselves to a set of fiscal priorities — lower taxes, higher defense spending, no entitlement changes for 210 years, and lower deficits — that can only be reconciled through draconian cuts to programs for the poor.

The result is that when Republican politicians stop speaking for themselves and begin speaking for their party, their fiscal proposals have to reflect those priorities, and so they end up cutting deep into programs for the poor, even though that may not be their personal preference. But that is, of course, just speculation.