For what is likely to be the best center-left case for President Obama’s reelection, read The New Republic’s endorsement, “Why Obamaism Must Live: The Case for Reelection,” part of which argues:

Health care reform, if it is properly nurtured, largely completes the social safety net. Financial reform, if the lobbyists don’t shred it, will curb maniacal risk-taking in the markets. The stimulus provided the seed money to launch Race to the Top–perhaps the most significant wave of experimentation in the history of public education–and to remake the energy grid. It created industries from scratch: biofuel refineries and plants that manufacture batteries for electric cars.
Obamaism itself is perhaps this administration’s most important innovation. The president has used New Democratic means to achieve Old Democratic ends. In pursuit of old liberal dreams, he has relied heavily on the insights of markets: spurring competition, reforming bureaucracies, and leveraging small investments to achieve big goals. Two of his signal programs–health care’s individual mandate and cap and trade–were tellingly conceived by conservatives.

While defending his moderate progressive policy agenda, The TNR editors fault the President for his inadequate salesmanship, particularly with respect to claiming due credit his “prescient” support for the Arab Spring and failing to strongly challenge the GOP’s wholesale government-bashing.
They also question his policy towards Afghanistan and Syria. But they give Obama due credit for his impressive foreign policy accomplishments:

The first term has a list of meaningful international accomplishments–chiefly his ruthless pursuit of Al Qaeda, the deft intervention in Libya, and the conclusion of the Iraq war. The president’s open hand to China and initial overtures to the Iranian regime have smartly been replaced by a new assertiveness. This willingness to change course has helped preserve American power in an era where it could easily have slipped away.

The President should also be credited, more specifically, with decisive leadership in ordering the raid that put an end to Osama bin Laden and hounding the al Qaeda leadership.
The TNR endorsement of President Obama scores sharply in directing readers to consider the dangerous alternative — “the virulence of the modern Republican Party”:

…Mitt Romney is the perfect avatar for a party in the throes of ideological convulsion. When he first considered running for president, in 2006, he seemed an archetype desperately missing from American politics. As a governor, he presented himself as a rigorous empiricist; his record formed a coherent pattern of bucking GOP orthodoxy on climate change, health care reform, and gay rights. But six years of pandering to Republican primary voters and donors will apparently distort even a first-rate mind. Far more than Ronald Reagan and George W. Bush, he has promoted a libertarian vision filled with substantive and rhetorical hostility to the poor. His foreign policy is similarly wild, urging the escalation of military hostility with nations who pose no meaningful strategic threat.

In acknowledging the President’s shortcomings, the TNR Editors conclude:

…Over the course of this campaign, he has emerged as a different kind of politician–a populist bruiser capable of skillfully and passionately assailing his opponents, while remaining indifferent to the hand wringing of establishment opinion. Perhaps this is a style better suited for the next four years, in which his primary task will be managing a fiscal crisis that his opponents will cynically exploit. Having extended the safety net, he must now protect it. Without a second term, the accomplishments of his first would evaporate. This is not a poetic rallying cry, but there is human suffering to be minimized and a new foundation to defend.

There is more that can be said both in the President’s favor and about the frightening dangers of the alternative. But if you know any undecided political moderates, show them the TNR editorial.