There is something darkly comic about John McCain trying to distance himself from George W. Bush.

After all, McCain is the man who first tried to spare the nation from a Bush presidency. South Carolina's derailment of McCain's 2000 campaign ranks somewhere beneath the unpleasantness at Fort Sumter as an act of national betrayal.

As a consequence, McCain has never been particularly close to Bush. In fact, during the last eight years, McCain has been one of the leading legislative voices attempting to constructively criticize - this is different from simply opposing - the president.

Yet, McCain is forced to remind voters of these facts because Democrats, and many in the media, pretend that he is running for "Bush's third term."

To put this to rest, McCain has requested that Bush scale back campaigning on his behalf. He has reiterated that the mistakes of civilian and military commanders in Iraq made him heartsick. He has even criticized Bush's ridiculous "Mission Accomplished" carrier-landing stunt.

None of this, however, is particularly substantive. At some point McCain will have to explain to voters what, exactly, he understands to be the Bush administration's successes and failures.

Three areas of Bush's tenure are obvious triumphs, upon which McCain should reasonably hope to build:

Stem Cells:

Bush's position was never, as his opponents characterized it, "anti-science." Rather, it was an assertion that society has a responsibility to guide science according to its mores.

Barely six years after Bush set guideposts on stem-cell research, science engineered a work-around that does not require the intentional creation and destruction of life. This is a happy outcome for all concerned, and Bush deserves immense credit for it.

Supreme Court:

Whatever one thinks of their judicial philosophies, it's hard to argue that John G. Roberts Jr. and Samuel A. Alito Jr. aren't the type of minds you want on the Supreme Court. Liberals might complain that they are too conservative, but that's a political quibble, not an intellectual one.

Afghanistan:

It was Bush's war of necessity and he waged it well, if not perfectly. Remember the pre-invasion talk about how Afghanistan was the "graveyard of empires"?

The coalition began the war on Oct. 7, 2001. Two months later, Hamid Karzai became the country's leader, replacing the Taliban. Liberalization proceeds, if not always in a straight line.

McCain can and should ally himself with each of these successes. Then there are Bush's failures. What follows is an incomplete list:

The housing meltdown:

It's never entirely fair to blame, or credit, a president for economic swings - the chief executive has only so much control over our gargantuan economy. But Bush deserves blame for ignoring what was obviously a bubble in the housing market.

In fact, during the 2004 campaign, Bush and his surrogates would not stop crowing about the record rates of home ownership - even though it was obvious those "record rates" were the result of bad loans being made to people who could not afford them.

Cronyism:

From Michael Brown to Monica Goodling, the administration had more than its share of hangers-on who were flatly unqualified for their posts. This happens in every administration; Bush had it worse than most.

The CIA:

Bush didn't make the CIA the mess it is, but he never expended political capital trying to fix it, instead squandering said capital on aborted Social Security and immigration policies. In the fight against terrorism, our intelligence service is as important as our armed forces. The next president inherits the same incompetent agency, and the nation is less safe as a result.

Iraq:

We can argue about its prudence, as you always can with wars of choice. We can declare with certainty that the war was poorly managed for three years. But if, a generation from now, Iraq is a liberalizing democracy exerting pressure on the autocratic, fundamentalist regimes of the Middle East, then the war will have been a success, despite everything. John McCain argued tirelessly for a change in strategy in Iraq, to give the war a chance of succeeding. So far, he has been proven correct.

The Bush presidency can at this point be fairly categorized as a failure. But to avoid being unfairly tied to Bush, it is not enough for McCain to put rhetorical distance between himself and the president. He should explain to voters both what the president did wrong and what the president did right.

In doing so he would reveal himself, again, as the most serious person running for president.

E-mail Jonathan Last at jlast@phillynews.com.