I am a proud progressive Democrat, someone who believes affordable, quality health care is an economic necessity and a moral imperative. As a longtime Democratic political strategist, I am skeptical, at best, of the Washington elite's worship of bipartisanship — as if the truth always lies halfway between Rush Limbaugh and Michael Moore.

And yet I think my fellow progressives ought to give Max Baucus and other members of the Senate Finance Committee a little breathing room as they labor to produce a health-care bill that can garner enough votes to pass the Senate.

Progressive politics is, in my view, a movement, not a monument. We cannot achieve perfection in this life, and if that is our goal we will always be frustrated. The right has far more modest goals: At every turn, its members seek to advance their power and protect privilege. I've never seen the Republican right oppose a tax cut for the rich because it wasn't generous enough; I've never seen them oppose a set of loopholes for corporate lobbyists because one industry or another wasn't included. The left, on the other hand, too often prefers a glorious defeat to an incremental victory.

Our history teaches us otherwise. No self-respecting liberal today would support Franklin Roosevelt's original Social Security Act. It excluded agricultural workers — a huge part of the economy in 1935, and one in which Latinos have traditionally worked. It excluded domestic workers, which included countless African Americans and immigrants. It did not cover the self-employed, or state and local government employees, or railroad employees, or federal employees or employees of nonprofits. It didn't even cover the clergy.

If that version of Social Security were introduced today, progressives like me would call it cramped, parsimonious, mean-spirited and even racist. Perhaps it was all those things. But it was also a start. And for 74 years we have built on that start. We added more people to the winner's circle: farmworkers and domestic workers and government workers. We extended benefits to the children of working men and women who died. We granted benefits to the disabled. We mandated annual cost-of-living adjustments. And today Social Security is the bedrock of our progressive vision of the common good.

Health care may follow that same trajectory. It would be a bitter disappointment if health reform did not include a public option. I believe subsidies should extend to as many Americans as need help and that the hard-earned health benefits of middle-class Americans should not be taxed. I believe insurer abuses like the preexisting-condition rule should be outlawed. The question is not whether I or other progressives will support a health-reform bill that includes everything we want but, rather, whether we will support a bill that doesn't.

Baucus and the others working on health care have earned the right to take their best shot, and we progressives should hold them to a high standard. I carry a heavy burden of regret from my role in setting the bar too high the last time we tried fundamental health reform. I was one of the people who advised President Clinton to wave his pen at Congress in 1994 and declare: "If you send me legislation that does not guarantee every American private health insurance that can never be taken away, you will force me to take this pen, veto the legislation, and we'll come right back here and start all over again." I helped set the bar at 100 percent — "guarantee every American" — and after our failure it's taken us 15 years to start all over again.

So I am trying to find the right blend of principle and pragmatism — ever mindful that, aside from race, health care is the most difficult domestic issue of the past century. FDR couldn't pass it. Nor could Truman, nor Nixon nor Carter nor Clinton. Lesser presidents like George W. Bush didn't even try.

The Founders gave us a standard: "a more perfect Union." It's an odd phrase; we don't generally speak of something becoming "more perfect." I believe it means that we have a duty, every generation, to make progress. For a dozen generations we have done that, in our imperfect way. Let's hope those writing the new health-reform bill can give us something that represents historic progress — and that those of us most passionately committed to fundamental reform can celebrate progress, not lament a lack of perfection.

Paul Begala is a Democratic strategist and political analyst. He wrote this commentary for The Washington Post.