Every week on the lecture trail I meet progressives who are demoralized and/or infuriated by Barack Obama's performance as president.

They insist that they will not work for him again or even vote for him. Many have signed petitions saying as much.

They are finished with Obama.

Often they assume that I agree, since I have criticized many of Obama's policies throughout his presidency. But my progressive friends and allies are overlooking three things:

1. Many of them played a disastrous role in the 2000 election, preventing the Gore administration that should have been.

2. Their charge of betrayal is exaggerated.

3. Obama, for all his temporizing and capitulation, is America's most progressive president since FDR, and electing a more compelling human being to the White House is probably impossible in this country.

America and the world would be better off today had there been a Gore administration. President Gore would not have invaded Iraq, showered the rich with tax cuts, doubled the federal debt, or let corporate lobbyists devise America's energy policies.

The left-liberals who sat out the 2000 election or that supported Ralph Nader had cause to be frustrated with Bill Clinton's legacy and put off by Gore's candidacy.

But the differences between the Gore administration that should have been, and the Bush administration that occurred, were enormous, vastly outstripping the reasons that progressives gave for spurning Gore.

As for betrayal, this charge registers surprise or double-dealing. But Obama has governed in the very manner of liberal-leaning moderation that he espoused in the 2008 campaign.

He never promised to get out of Afghanistan, scale back the military empire, or break the banking oligarchy.

His campaign supported a public option in health care, but very quietly, and he talked about persuading Democrats and Republicans to work together, not about fighting for social justice causes.

Obama did not have a single risky position in his campaign agenda. But too many progressives and others imagined they were electing Martin Luther King, Jr., which set them up for a mighty disillusionment.

To be sure, Obama has made brutal concessions that he never promised, mostly in hostage situations. Some are too brutal to be cleaned up even by the "hostage" explanation.

He cut Medicaid to get a budget deal, carrying on the Beltway tradition of bashing poor people first. He offered to increase the entry age for Medicare, which is the opposite of what America needs to do in health care.

He cut an atrocious deal in the debt ceiling fiasco as though he lacked any leverage, giving Republicans (on House Speaker John Boehner's estimate) 98 percent of what they wanted.

Now we are grinding through a miserable season of cutting federal spending in a struggling economy, which is self-defeating.

It is hard to remember the feeling of November 2008 that a new era was beginning. But it is not too late for that to happen.

Obama is still a figure of singular promise in American politics and he has important accomplishments to build upon -- achievements that too many progressives and others fail to acknowledge. Consider this:

- Obama abolished the United States' use of torture and the CIA's secret prisons.

- He restored the liberal internationalist approach to foreign policy and made an historic outreach to the Muslim world.

- He stabilized an economy that was spiraling into a depression.

- He expanded the Earned Income Tax Credit and made major investments in job training, education, infrastructure, clean energy, housing, and scientific research.

- He saved the automobile industry by saving General Motors and Chrysler.

- He forced the health insurance companies to stop excluding people with pre-existing conditions and to stop dropping people when they got sick.

- He made an enormous and historic gain toward universal health care.

- He signed a financial reform bill that established a consumer protection agency and put most derivative trading on an open exchange under the regulatory umbrella.

- He ended the war in Iraq exactly as he promised.

- He helped to inspire, and adeptly responded to, a wave of democratic revolutions in the Arab world.

- He relieved the world of Usama bin Laden and helped to end the murderous regime of Muammar Qaddafi.

- He ended the Pentagon's "Don't Ask, Don't Tell" mistreatment of gays and lesbians in the military.

- He blocked Republicans from eliminating federal funding for Planned Parenthood.

- He suspended deportation proceedings against illegal immigrants lacking a criminal record.

- He has supported family unity in immigration policy, interpreting "family" to include the partners of lesbian, gay, and bisexual people.

- He stood up to the oil lobby on the Keystone Pipeline.

- He has represented the United States with consummate dignity.

Somehow all of this is routinely discounted or forgotten, even as the Republican Party has lurched wildly to the right.

If Obama does not win a second term, a Republican administration will savage Medicare and Medicaid, enact yet another massive tax cut for the one percent, and try to privatize Social Security.

Obama, for all his shortcomings, is still indispensable to the cause of ending the Reagan era, and of preventing something even worse than the administration that Obama succeeded.

Gary Dorrien is Reinhold Niebuhr Professor of Social Ethics at Union Theological Seminary and Professor of Religion at Columbia University. His many books include "Kantian Reason and Hegelian Spirit" (Wiley-Blackwell, 2012) and the forthcoming "Obama in Question: A Progressive Perspective" (Rowman & Littlefield).