President Bush’s legacy has received renewed attention as the result of the opening of his presidential library. The Washington Post’s Jennifer Rubin uses a new poll showing Bush’s approval rating creeping up to 47 percent as a jumping off point for a full-throated defense of his time in office. This part jumped out at me: “He is responsible for one of the most popular and fiscally sober entitlement plans, Medicare Part D. He did not foist a grandiose unpopular and exorbitant program like Obamacare on the public.”

Saying that Medicare Part D is a “fiscally sober entitlement plan” is sort of like saying that somebody is quite temperate — for a heroine addict. In 2011, according to the Medicare Trustees, the federal government spent $53 billion on prescription drug subsidies through the program. None of that is paid for either through a revenue stream or cuts to existing government programs. However inadvisable or difficult to implement, Obamacare did include tax hikes and cuts to projected Medicare spending to pay for its new expenditures. With Medicare Part D, Bush didn’t even pretend that the law paid for itself on paper.

Also, as the chart demonstrates, the cost of the program to the federal government is projected to accelerate over time, reaching $117 billion in 2021. By comparison, Obamacare’s new insurance exchanges are expected to cost a similar $122 billion that year. Bush’s defenders might argue that Obamacare boosted Medicare Part D spending by making the subsidies more generous, which helps account for part of the projected growth of the program over the next decade. But I don’t view that as much as an excuse, because history has taught us that government programs expand over time, and if Bush didn’t consider this possibility in his drive to pass Medicare Part D before the 2004 election, that’s his own fault. In the long-run, Medicare Part D is running a $14.3 trillion deficit.

In his second term, Bush set out to reform Social Security. But his actual legacy on entitlements will be the largest (pre-Obamacare) expansion of them since Lyndon B. Johnson created Medicare and Medicaid in 1965. This, of course, is only a part of Bush’s disastrous fiscal record, which saw the federal budget spike from $1.86 trillion in 2001 to $2.98 trillion in 2008.

Bush’s legacy isn’t something for conservatives to celebrate. It’s something for them to mourn.