That a tsunami of anger is gathering today is illogical, given that what the right calls “Obamacare” is less provocative than either the Civil Rights Act of 1964 or Medicare, an epic entitlement that actually did precipitate a government takeover of a sizable chunk of American health care. But the explanation is plain: the health care bill is not the main source of this anger and never has been. It’s merely a handy excuse. The real source of the over-the-top rage of 2010 is the same kind of national existential reordering that roiled America in 1964.

In fact, the current surge of anger  and the accompanying rise in right-wing extremism  predates the entire health care debate. The first signs were the shrieks of “traitor” and “off with his head” at Palin rallies as Obama’s election became more likely in October 2008. Those passions have spiraled ever since  from Gov. Rick Perry’s kowtowing to secessionists at a Tea Party rally in Texas to the gratuitous brandishing of assault weapons at Obama health care rallies last summer to “You lie!” piercing the president’s address to Congress last fall like an ominous shot.

Image Frank Rich Credit... Fred R. Conrad/The New York Times

If Obama’s first legislative priority had been immigration or financial reform or climate change, we would have seen the same trajectory. The conjunction of a black president and a female speaker of the House  topped off by a wise Latina on the Supreme Court and a powerful gay Congressional committee chairman  would sow fears of disenfranchisement among a dwindling and threatened minority in the country no matter what policies were in play. It’s not happenstance that Frank, Lewis and Cleaver  none of them major Democratic players in the health care push  received a major share of last weekend’s abuse. When you hear demonstrators chant the slogan “Take our country back!,” these are the people they want to take the country back from.

They can’t. Demographics are avatars of a change bigger than any bill contemplated by Obama or Congress. The week before the health care vote, The Times reported that births to Asian, black and Hispanic women accounted for 48 percent of all births in America in the 12 months ending in July 2008. By 2012, the next presidential election year, non-Hispanic white births will be in the minority. The Tea Party movement is virtually all white. The Republicans haven’t had a single African-American in the Senate or the House since 2003 and have had only three in total since 1935. Their anxieties about a rapidly changing America are well-grounded.

If Congressional Republicans want to maintain a politburo-like homogeneity in opposition to the Democrats, that’s their right. If they want to replay the petulant Gingrich government shutdown of 1995 by boycotting hearings and, as John McCain has vowed, refusing to cooperate on any legislation, that’s their right too (and a political gift to the Democrats). But they can’t emulate the 1995 G.O.P. by remaining silent as mass hysteria, some of it encompassing armed militias, runs amok in their own precincts. We know the end of that story. And they can’t pretend that we’re talking about “isolated incidents” or a “fringe” utterly divorced from the G.O.P. A Quinnipiac poll last week found that 74 percent of Tea Party members identify themselves as Republicans or Republican-leaning independents, while only 16 percent are aligned with Democrats.

After the Civil Rights Act of 1964 was passed, some responsible leaders in both parties spoke out to try to put a lid on the resistance and violence. The arch-segregationist Russell of Georgia, concerned about what might happen in his own backyard, declared flatly that the law is “now on the books.” Yet no Republican or conservative leader of stature has taken on Palin, Perry, Boehner or any of the others who have been stoking these fires for a good 17 months now. Last week McCain even endorsed Palin’s “reload” rhetoric.