Until now, the only House Republicans pushing for a government shutdown and debt crisis were a few dozen on the radical right, the ones Senator Harry Reid, the majority leader, referred to as “the anarchists.” On Wednesday, however, the full Republican caucus, leadership and all, joined the anarchy movement, announcing plans to demand the defunding of health care reform as the price for keeping the government open past Sept. 30.

The decision means that a government shutdown next month is now much more likely. In the past, shutdown threats were averted because Republican leaders were willing to negotiate on spending issues, though the spending cuts that resulted were often harmful to important programs. But the health law is not negotiable for President Obama and the Democrats. By choosing this as their live-or-die issue, Republicans are driving straight toward the brink and removing the brake pedal.

What is worse, the House leadership also announced plans to make a series of demands of the White House in exchange for raising the debt ceiling in mid-October, threatening a government default if they don’t get their way. The demands, announced by the majority leader, Eric Cantor, are a goodie-bag of Republican priorities: approving the Keystone XL oil pipeline, delaying health reform by a year, and changing the tax code in ways that will undoubtedly benefit corporations and the wealthy.

Mr. Obama has said that he will not negotiate on raising the debt ceiling. “What I will not do is to create a habit, a pattern, whereby the full faith and credit of the United States ends up being a bargaining chip to set policy,” he said on Wednesday morning. If Republicans don’t back down, the double blow of a government shutdown, followed by a default, would be ruinous to the economy.