Note: A shorter version of this essay appears in today’s edition of the Wall Street Journal.

President Barack Obama takes office at a time defined by hope and fear in equal measure. To confront this nation’s many challenges he will need to act swiftly, show that he is on the side of people whose homes are being foreclosed and jobs lost and invest political capital–along with trillions of dollars–in a sustained recovery program. While many caution our new President to tread carefully, the reality is that half-steps will not lay the groundwork for a new economy that is more just and fair. Only by effectively marshaling the power of government can Obama improve the actual conditions of peoples’ lives–and consign anti-government evangelists to the dustbin of history.

Fortunately, Obama has a mandate for change. People support reconstruction of America’s crumbling physical infrastructure, and of our society. Here are a few steps I hope President Obama will take: Reverse our deepening economic inequality by using this country’s still immense wealth to assure that all Americans have the healthcare, housing and education they need; reengage the world with wisdom and humility about the limits of military power; cut billions from wasteful defense budgets that empty our treasury without making us more secure; tackle the deep corruption in a financial system that consistently favors corporations over workers; respond with urgency to the climate crisis with an Apollo-like project to make America a clean-energy innovator; restore our tattered constitution; protect a worker’s right to organize; define a new spirit of sacrifice and service; clean up our elections; and reaffirm his campaign-trail commitment to end not just the war in Iraq but also “end the mindset that took us into” that war. Do not endanger the promise of this Administration by escalating militarily in Afghanistan, further draining resources that are vital for rebuilding here at home and impede critical international initiatives such as renewing the Middle East peace process.

That’s a bold agenda millions can believe in. In fact, it’s what millions voted for. This new President does not have to pull his punches, and Americans do not have to settle for less. As the first Community -Organizer-in-Chief, Obama understands the power of change from below. He has oxygenated the grassroots and got people believing and dreaming again. But he will only be as brave as ordinary citizens move him to be. That’s why independent small d- democratic movements, grassroots organizing, online and offline, will be vital to pushing the limit of Obama’s own politics and countering the forces of money and establishment power which remain obstacles to meaningful reform. A savvy inside-outside political strategy, engaging the new Administration and Congress constructively, even as progressives push for solutions on a scale necessary to deliver, will be critical if we are to fulfill the promise of relief, reform and reconstruction.

We celebrate the beginning of a new era, and we recognize that the fate of an Obama Presidency may well be determined by how audacious he chooses to be. During the campaign, our new President told us that real change comes about by “imagining and then fighting for and then working for what did not seem possible before.” If Americans keep fighting for that change, we can reaffirm our expectations of our new President, and together complete the unfinished work of making America a more perfect union.