O.K., folks, this is it. It’s the defining moment for health care reform.

Past efforts to give Americans what citizens of every other advanced nation already have  guaranteed access to essential care  have ended not with a bang, but with a whimper, usually dying in committee without ever making it to a vote.

But this time, broadly similar health-care bills have made it through multiple committees in both houses of Congress. And on Thursday, Nancy Pelosi, the speaker of the House, unveiled the legislation that she will send to the House floor, where it will almost surely pass. It’s not a perfect bill, by a long shot, but it’s a much stronger bill than almost anyone expected to emerge even a few weeks ago. And it would lead to near-universal coverage.

As a result, everyone in the political class  by which I mean politicians, people in the news media, and so on, basically whoever is in a position to influence the final stage of this legislative marathon  now has to make a choice. The seemingly impossible dream of fundamental health reform is just a few steps away from becoming reality, and each player has to decide whether he or she is going to help it across the finish line or stand in its way.

For conservatives, of course, it’s an easy decision: They don’t want Americans to have universal coverage, and they don’t want President Obama to succeed.