WASHINGTON – Three front-page headlines on a single day last week testified to the unraveling of the Bush presidency.

The lead story in The Washington Post on Thursday reported that “the Senate defied the White House Wednesday and voted to set new limits on interrogating detainees in Iraq and elsewhere,” with 46 Republicans joining the Democrats to pass restrictions on prisoner abuse so unacceptable to President Bush that he has threatened his first-ever veto.

A second story on the same page recounted that “the conservative uprising against President Bush escalated Wednesday as Republican activists angry over his nomination of White House Counsel Harriet E. Miers to the Supreme Court confronted the president’s envoys during a pair of tense closed-door meetings.” Participants described it as the biggest split with the GOP base in Bush’s five years in office.

And elsewhere on the page was the news that the CIA’s director had rejected a recommendation from the inspector general that he convene a formal “accountability board” to judge the possible complicity of senior officials in the failures that preceded the Sept. 11, 2001, terrorist attacks. The action triggered a statement of concern from the Republican chairman of the Senate Intelligence Committee and criticism from families of 9/11 victims.

These developments came against a background of rising conservative criticism in Congress of runaway spending, of continuing investigations of the Bush administration’s faltering response to Hurricane Katrina and of criminal indictments and grand jury probes that have forced out the chief White House procurement officer and the House Republican majority leader and may implicate other top officials of both branches of government.

Coming at a time when Bush is recording his lowest-ever job-approval scores, this has led as sober an analyst as John Kenneth White of Catholic University to describe this as “a presidency on life support.” Noting the precipitous decline in Bush’s ratings among moderates and independents, White argues that continuing problems – notably, the war in Iraq, the high cost of gasoline and home heating fuels and an unending stream of deficits – are likely to plague Bush for the foreseeable future.

A valuable historical perspective on all this came from Stephen Skowronek of Yale University in a talk to the American Political Science Association just before Labor Day. At the time, it seemed a bold – even questionable – thesis. Now, it looks prescient.

Skowronek, a presidential scholar, defined Bush as “an orthodox innovator,” meaning someone who inherits a governing doctrine from others (in his case, Ronald Reagan) but applies it in different circumstances and with different techniques.

Other presidents of the same ilk, he said, include James Polk, Theodore Roosevelt and Lyndon B. Johnson. Johnson, for example, took a number of ideas that had been on the shelf since New Deal days and tried to apply them to a hugely different time, succeeding spectacularly with a Medicare plan rooted in Social Security but failing disastrously when he applied the analogy of Adolf Hitler to Ho Chi Minh.

Skowronek said that historically, what leads to ultimate failure for orthodox innovator presidents is “sectarian infighting.” They fail, he said, not because the political opposition becomes so strong but because their own supporters fall out among themselves – some insisting on the original orthodoxy of the inherited philosophy, others demandingchange to adapt to new conditions.

When Skowronek spoke barely a month ago, I was skeptical. But now, such strains are plainly visible inside Bush’s coalition. Some fiscal conservatives are demanding a return to smaller government and balanced budgets while others – neoconservative hawks and worried Southern elected officials – back Bush in pledging “whatever it takes” to win in Iraq and repair the Gulf Coast.

Similarly, among social conservatives, some no longer are satisfied with Bush’s personal assurances that his tight-lipped Supreme Court choices actually will roll back the school-prayer, affirmative-action and abortion rulings now in effect, while others applaud Bush for taking what they regard as the course of prudent ambivalence.

Skowronek said the long rivalry between Bush and Sen. John McCain, R-Ariz. – something that flared again in last week’s fight over the treatment of detainees – is reminiscent of the battles between Polk and Martin Van Buren, LBJ and Robert Kennedy – fights which split their parties wide open. But he also noted that the unprecedented organizational strength and top-down control of the Republican Party forged in the Bush years served for a long time to keep these internal pressures from erupting.

Whether that discipline will continue to hold through Bush’s lame-duck years is another – and very different – question. It must be keeping Karl Rove awake at night.