President Bush never has been said to excel at “nuance.” Yet his relationship with Congress in the past four years has left the fuzziest of impressions.

Depending on whom one speaks with, this president is either the most deferential or the most arrogant leader Capitol Hill has seen in generations; the president who dutifully observes Congressional prerogatives, or ruthlessly imposes his will; the president who values the policy judgments of his legislative peers, or resists even the most benign oversight requests.

As it is with the man himself, so it would seem with those who have observed his term in office from Capitol Hill: very little gray area.

“There is no oversight of the Bush administration,” said Rep. John Dingell (D-Mich.), one of the more persistent wielders of Congressional prerogative.

“Sometimes they answer your mail, but more often not. Sometimes they’re actively deceitful in what they tell us,” Dingell said, adding, “Other administrations have been much more open, much more forthcoming, much more truthful.”

As the Democrats see it, the dereliction began almost at day one, with the energy task force convened at the White House by Vice President Cheney in 2001. Over four years, Democrats have poked fruitlessly at the group, seeking everything from its minutes to a simple roster of participants.

Democrats say the pattern has endured through Bush’s term in office, to the point where one ranking member — Rep. Henry Waxman (D-Calif.) of the Government Reform Committee — sought to compile an authoritative record of what Democrats considered noncooperation.

Republicans argue that such dramatics are all part of the normal give-and-take between Congress and the executive branch.

“Congress always complains about” being disregarded, said Grover Norquist, a top GOP strategist. “Ask the Democratic Congress under [former President Jimmy] Carter. They were always bouncing off the walls.”

Added another Republican strategist with close ties to the White House, “Please, please identify the presidency where Congress gave the president kudos for the way he reached out to Congress. … I don’t think there’s anything profound in the griping.”

In fact, if there is a flaw Republicans — particularly conservatives — detect in the way Bush has dealt with Congress, it is that he has deferred too often to the judgment and appetites of lawmakers.

Bush’s White House stood aside as Congress wrote and passed bills to change the campaign finance system and to ratchet up corporate governance — two of the most significant and far-reaching pieces of legislation in the past four years. The president then signed those measures, despite protests from his own party that the bills contained language that undercut the “principles” that Bush himself had laid out beforehand.

In fact, in his deployment of the one tool a president can use to control Congress — the veto — Bush has been downright kittenish.

If affairs continue on their current path, this president will become the first since James Garfield in the 1880s to not use this constitutional prerogative. (Bush has, however, threatened to veto the reauthorization of the highway bill if lawmakers do not slash its cost. The dispute may delay passage of the legislation until at least the next Congress.) Many conservatives blame spiraling deficits on Bush’s refusal to use his veto.

So, is this the behavior of an imperial executive who does not recognize Congressional authority?

“I think there’s this mixture of naïvete and arrogance here,” said Paul Light, a political scientist at New York University who admits to being puzzled by the relationship that has emerged between Bush and Congress.

On one hand, Light said, Bush’s failure to use his veto pen sends a message of weakness to Congress. “Administrations sometimes use the veto just to show Congress they have that power and will use it,” he said.

But the flip side has been the White House’s demonstrated willingness to circumvent that process when Congress won’t give the president what he wants.

Light cited the president’s “faith based” initiative, a plan that would enable religious groups to compete for federal dollars that are set aside for drug abuse and other treatment programs.

When Congress turned down some requests from the administration, the White House sought to use executive orders and other instruments that would enable the president to circumvent the legislative branch.

“They’ve used administrative tools quite aggressively. And I don’t know whether they don’t understand Congress or whether they just want things to get done more quickly” than Congress has been willing to do them, said Light. His own strong hunch is that the Bush White House lacks a “fundamental respect” for Congress as an institution.

What’s equally curious to some Congressional observers is what they consider the limp response from Capitol Hill in instances where the administration has, by some lights, deceived them. One recent example they cite is the controversy surrounding the administration’s decision not to reveal internal figures that suggested last session’s Medicare law could be costlier than advertised.

As the argument goes, although lawmakers typically go easier on presidents from their own party, they nonetheless recognize that the power of Congress — and thus, their own power as legislators — depends on their willingness to assert institutional prerogatives.

“Maybe they’ve all become Hamiltonians,” Light said wryly, suggesting that Republicans suddenly want to concentrate federal power. “It’s going to take some time to figure out what’s actually happened here.”

A spokesman for Speaker Dennis Hastert (R-Ill.) disputed the contention that Congress had allowed its oversight responsibility to lapse, and countered that it has in fact strongly asserted its powers in instances where it is warranted, such as with matters related to the war on terror.

“What there’s not is partisan witch-hunts,” said the spokesman, John Feehery. “That’s one good reason to have both the Congress and administration in Republican hands.”

Feehery nevertheless acknowledged that power has shifted strongly toward Bush’s White House in the past four years. He chalked that up to the war effort.

“Wartime presidents tend to gain more power,” Feehery said. “When you’re fighting a war, you want to put more faith in the executive branch.”

University of Wisconsin political scientist Charles Jones suggested that it is difficult to gauge the extent to which power has shifted because Washington has seen five different governing arrangements since 1992 — three during Bush’s term alone.

The Sept. 11, 2001, terrorist attacks added an additional variable to the mixture.

“It was a priority reordering event unlike any we’ve had in recent times,” Jones said. The attacks “provided the context in which everything else would be judged.”

The immediate effect, Jones said, was a “dramatic change” in the president’s legitimacy — and thus, his power on Capitol Hill. Prior to that event, Jones said, Bush ranked dead last in terms of political power by one measure, which includes as its criteria the president’s popular vote and electoral vote percentages, along with his job-approval rating. But the attacks gave Bush substantial leverage in setting the agenda, especially in matters related to the war on terror.

“What’s a little puzzling is why there hasn’t been more use of the veto threat,” Jones said. “It suggests they may not have a firm position” on the issues before Congress.

The narrowness of the Republican majority in Congress may play a part in these ambiguities. Scholars suggest that this thin margin of control places a premium on party discipline, because breakaways can in effect hand the minority control over the agenda. In this scenario, it is also important for the majority to protect and fortify the president, because the strength of their agenda depends on the credibility of the president who is selling it.

Senate Historian Richard Baker describes smooth relations between the branches as “the exception rather than the rule.” The most notable of these exceptions occurred in the “100 Days” Congress of 1933, when newly elected President Franklin Delano Roosevelt took advantage of huge Congressional majorities to ram through the programs that formed the New Deal.

But there have been very few instances of such comity between the branches in the ensuing decades.

In fact, it was not long before Roosevelt himself sparked one of the more consequential struggles between the branches. When then-Senate Majority Leader Alben Barkley (D-Ky.) balked at a request for a massive increase in funding for the ongoing war effort, Roosevelt declared he would spend the money anyway.

Barkley resigned in protest but was quickly reinstated as leader by his Caucus. The episode transformed Barkley’s image and role. He was no longer seen as the president’s messenger to Congress; he became the conveyor of Congressional will — a shift that put institutional fidelity above partisan obligation.

“The Constitution is an invitation to struggle,” Baker said, quoting a political scientist from FDR’s time.