Apart from his political skills, two forces above all have propelled Barack Obama in his once-improbable quest for the presidency.

One is on vivid display this week: a wave of dissatisfaction with the country's direction that has created a visceral demand for change. That wave has reached towering heights amid

the financial crisis roiling Wall Street and consuming Washington. No other candidate has drawn more power than Obama has from that desire to shift course.

With much less fanfare, this week also marked a milestone in the evolution of the second force that has lifted Obama: the rise of the Internet as a political tool of unparalleled power for organizing a vast activist and donor base.

Ten years ago this week, Wes Boyd and Joan Blades, two California-based software developers (their company created the "Flying Toaster" screensaver), posted an online petition opposing the drive by congressional Republicans to impeach President Clinton. The one-sentence petition urged Congress instead to censure Clinton and "move on." Within days the couple had collected hundreds of thousands of names. Thus was formed MoveOn.org, the first true 21st-century political organization.

Born fighting, MoveOn has become the point of the spear for the Democratic Left through eight years of combat with President Bush over issues from Iraq to Social Security. No group has been more influential, innovative, or controversial in devising the Internet-based organizing strategies that are precipitating the new age of mass political participation symbolized by Obama's immense network of contributors and volunteers. "In the evolution of this, they were there at the very beginning," says veteran Democratic strategist Joe Trippi.

MoveOn's political impact must be measured on two levels: message and mechanics. The group's techniques draw praise in both parties. Boyd and Blades, and later Eli Pariser, a young organizer who has become MoveOn's leading force, recognized that the Internet created unprecedented opportunities for organizing. Traditionally, causes and candidates faced daunting expenses in trying to find like-minded people through advertising, direct mail, or canvassing. But the Internet reversed the equation: Once MoveOn established itself at the forefront of liberal activism, millions of people who shared its views found it at little (or no) cost to the group.

Indeed, MoveOn quickly discovered that the more fights it pursued, the more names it collected -- and the more it increased its capacity to undertake new campaigns. "There's this old model of political capital: Every time you fight, you are spending something," Boyd says. "Our observation was: Whenever we fight, we get stronger."

Fueled by this dynamic, MoveOn routinely generates levels of activity almost unimaginable not long ago. Since 1998, it has raised $120 million; it mobilized 70,000 volunteers for its get-out-the-vote effort in 2004, and might triple that number this year. It now stands at 4.2 million members, after adding 1 million, mostly through social-networking sites, this year.

The purposes to which MoveOn applies these vast resources are more debatable. The group has become a favored target for Republicans and a source of anxiety for some Democratic centrists, who worry that it points the party too far left. On domestic issues, it fits within the Democratic mainstream. But on national security, it defines the party's left flank. MoveOn resisted military action not only in Iraq but also in Afghanistan. And on both foreign and domestic concerns, it often frames issues in terms so polarizing that it risks alienating all but the most committed believers. The group's lowest moment came in 2007 when it bought a newspaper ad disparaging Gen. David Petraeus, the U.S. commander in Iraq, as "General Betray Us" on the grounds that he would attempt to mislead Congress about the war. Petraeus's brilliant subsequent progress in stabilizing Iraq has only magnified the unseemliness of that accusation. "I wouldn't have done the headline the exact same way," Pariser now concedes.

Still, as candidates and groups in both parties adapt its strategies for online organizing, MoveOn can justly claim a central role in igniting the surge in grassroots activism that is transforming American politics. "Regardless of your political convictions, you have to feel like this is a very healthy thing for democracy," Pariser says. MoveOn's causes may divide, but Democrats and even many Republicans are increasingly uniting around the bottom-up vision of political change that these ardent activists have helped to revive.

This article appeared in the Saturday, September 27, 2008 edition of National Journal.

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