During the 2008 campaign, Paul Krugman was one of Barack Obama's most relentless critics. Relations between the campaign and the economist got so bad that Team Obama actually dropped an oppo document on Krugman.

Which did not help.

After Obama's election, Krugman became something of a liberal frenemy to the administration: he was a much-sought ally, and a much-feared critic. Krugman's criticisms burned because the White House often agreed with them — they also wanted a larger stimulus, and a better health-care bill; they just thought the New York Times economist didn't appreciate the electric fence of political reality.

Krugman became something a liberal frenemy to the administration

Krugman, for his part, thought the administration too fearful of the Very Serious People and too optimistic about the right. It's a criticism he partially resurrects in a new Rolling Stone piece. "Obama was indeed naive," Krugman writes. "He faced scorched-earth Republican opposition from Day One, and it took him years to start dealing with that opposition realistically."

Krugman: Obama a historic success

Even so, Krugman says, "Obama has emerged as one of the most consequential and, yes, successful presidents in American history. His health reform is imperfect but still a huge step forward - and it's working better than anyone expected. Financial reform fell far short of what should have happened, but it's much more effective than you'd think. Economic management has been half-crippled by Republican obstruction, but has nonetheless been much better than in other advanced countries. And environmental policy is starting to look like it could be a major legacy."

Hate Obama or love him, on this, Krugman is clearly correct. Obama has passed more major legislation than perhaps any president since Lyndon Johnson — and, at least as of yet, there's no Vietnam War to mar his legacy. The history of the Obama administration will be hard to write, as so many of its chapters will demand their own books (indeed, some, like the stimulus, have already gotten them). Most crucially, Obamacare itself looks headed for success — and that, plus preventing the financial crisis from turning into another Great Depression, is a legacy in itself.

That said, Obama's greatest successes — and his most serious failures — lie in the dense mass of his first two years. This is the time, in Krugman's telling, before Obama grokked the nature of the Republican opposition and "began dealing with it realistically." I think the story there is more complicated — and more interesting.

Obama, while seeking the post-partisan presidency he wanted, established the brutally partisan presidency he got

From 2009 to 2010, Obama, while seeking the post-partisan presidency he wanted, established the brutally partisan presidency he got. Virtually every achievement Krugman recounts — the health-care law, the Dodd-Frank financial reforms, the financial rescue, the stimulus bill — passed in these first two years when Democrats held huge majorities in congress. And every item on the list passed over screaming Republican opposition. The first two years of the Obama administration are the story of Obama being haunted by his promises of a postpartisan presidency, and choosing, again and again, to pass bills at the cost of worsening partisanship.

The irony of Obama's presidency

As Reid Cherlin, a former Obama administration staffer, put it, "[T]hey have managed over six years to accomplish much of what Obama promised to do, even if accomplishing it helped speed the process of partisan breakdown." The engine of Obama's political rise, going all the way back to his 2004 keynote at the Democratic National Convention, was that the conflictual nature of politics was the product of the people who knew no politics other than conflict. The central irony of Obama's presidency is he proved himself wrong.

Obama promised to reform the health-care system and regulate the financial sector by fixing American politics. Instead, he did it by breaking American politics further. The candidate who ran for office promising to heal Washington's divisions became the most divisive president since the advent of polling:

It's not just partisanship. Obama ran as the scourge of special interests. "We can't keep playing the same Washington game with the same Washington players and expect a different result," he said. "Because it's a game that ordinary Americans are losing. It's a game where lobbyists write check after check and Exxon turns record profits, while you pay the price at the pump, and our planet is put at risk."

Lobbyists still write their checks in Obama's Washington. The health-reform bill got done by cutting side deals with pharmaceutical companies and insurers. Dodd-Frank got done by cutting side deals with auto dealers and mutual funds. The Obama administration has put no political capital behind major campaign-finance reforms or, really, any other ideas that would fundamentally change how Washington works. It's the same old Washington game with the same old Washington players — but Obama, when he had his big congressional majorities, managed to secure a different result.

Obama kept his policy promises by sacrificing his central political promise

Obama spent his first two years keeping many of his policy promises by sacrificing his central political promise. That wasn't how it felt to the administration at the time. They thought that success would build momentum; that change would beget change. Obama talked of the "muscle memory" Congress would rediscover as it passed big bills; he hoped that achievements would replenish his political capital rather than drain it.

In this, the Obama administration was wrong, and perhaps naive. They overestimated their ability to convert the raw exercise of political power into more political power. It was a mistake, but not a very postpartisan one. And, as a theory, it was the one they needed to build their legacy — a legacy, at this point, that even their early critics admire.

"I don't care about the fact that Obama hasn't lived up to the golden dreams of 2008, and I care even less about his approval rating," writes Krugman. "I do care that he has, when all is said and done, achieved a lot."