Here is what the Chronicle says about their choice:

The American political system needs a period of reprieve and renewal.

It needs a reprieve from a White House that draws power from fear, sneers at any science that gets in the way of corporate or theocratic missions and stubbornly adheres to policies that leave the nation sinking in debt and mired in war. It craves a reprieve from the politics of bloodsport that prize clever calculation over courage, winning over principle, party label over national interest.

The renewal must come from a president who can lead by inspiration, who can set partisanship aside to define and achieve common goals, who can persuade a new generation of Americans that there is something noble and something important about public service.

There is no doubt about the Democrat with the vision and skills to bring that period of reprieve and renewal. It is Sen. Barack Obama.

As is often the case in a heavily contested primary, the relatively modest policy differences among the candidates have become magnified and inflamed beyond all due perspective. For example, Obama, Sen. Hillary Rodham Clinton and Sen. John Edwards have pledged to expand health coverage, albeit with somewhat different approaches. Obama’s is certainly the most cautious, though perhaps the most realistic, considering that any overhaul of the health care system would require buy-in from at least some Republicans and myriad business interests that would be affected by such landmark federal regulation.

All three have vowed to phase out the U.S. military presence in Iraq. Obama, however, stands alone in his opposition to the invasion at the outset. Clinton and Edwards each voted to give President Bush the authorization to use military force against Saddam Hussein. Edwards acknowledges his mistake, Clinton parses the meaning of the resolution. It was Obama’s instincts that proved sound.

Clinton, who arrived in the U.S. Senate four years before Obama, has tried to make experience the issue. As senator, she has proved skillful at representing diverse New York interests and working with Republicans. But if she wants to highlight her White House experience as a defining difference, then it’s only fair to point out that two of the projects she was most deeply involved with produced a debacle (health care) and scandals (fund raising). Especially in recent days, her campaign has shown the sharp elbows that evoke the ugly underside of the Clinton years, and the (Karl Rove inspired) Bush years that succeeded them: the reflex to scorch the Earth, to do what is necessary to vanquish political adversaries … all is justified if you are left standing at the end.

America deserves better than these cycles of vengeance and retribution. Its possibilities are too great, its challenges too daunting, for partisan pettiness.

In a Jan. 17 meeting with our editorial board, Obama demonstrated an impressive command of a wide variety of issues. He listened intently to the questions. He responded with substance. He did not control a format without a stopwatch on answers or constraints on follow-up questions, yet he flourished in it.

He radiated the sense of possibility that has attracted the votes of independents and tapped into the idealism of young people during this campaign. He exuded the aura of a 46-year-old leader who could once again persuade the best and the brightest to forestall or pause their grand professional goals to serve in his administration.

Of all the candidates who talk about change, Barack Obama has made the case most forcefully and most convincingly. He gets our endorsement for the Democratic nomination.