Rep. Ernest J. Istook Jr.'s pocket-size copy of the U.S. Constitution is rarely out of his reach, with the paragraph detailing the federal government's supreme control over the District of Columbia highlighted in fluorescent yellow.

"The Congress shall have the power to . . . exercise exclusive legislation in all cases whatsoever over such District," said Istook, quoting his favorite line while sitting in his Capitol Hill office last week.

It may seem like an ominous refrain, given Istook's assignment as chairman of the House Appropriations panel that holds the District's purse strings. But as he wraps up his first budget cycle in the high-profile post, the deeply religious, anti-gay Republican from Oklahoma has proved, even to his critics, to be surprisingly flexible.

Mayor Anthony A. Williams (D) and D.C. Council Chairman Linda W. Cropp (D) each recall hours of telephone consultations with Istook, during which he worked to ensure that the bill he was moving through Congress did not offend them--at least when it came to city finances. In the end, Istook's committee left the District's $4.7 billion budget essentially untouched--except for $95 million added to selected city programs.

Del. Eleanor Holmes Norton (D-D.C.) and Virginia Rep. James P. Moran Jr., the ranking Democrat on the House D.C. panel, had similar encounters. The most poignant one came in the final minutes before the full House vote on Thursday, when Istook offered to push for a softening of a GOP-backed provision in the D.C. budget bill that would ban city spending on the District's voting-rights lawsuit.

"Here is an example of a right-wing ideologue maturing to the point where he should rightfully be considered a serious legislator," Moran said, begrudgingly offering praise.

Istook, 49, never withdrew his support for GOP-backed riders attached to the budget that were aimed at prohibiting the city from legalizing marijuana for medical purposes, spending city funds on abortions or providing clean needles to drug addicts, among other restrictions. But he prevented additional riders from being attached, allowing only items approved by the House last year to reach the floor.

"I felt we needed to focus on the things where we were together," Istook said.

City leaders were skeptical when Istook became chairman of the D.C. Appropriations subcommittee in January. He replaced another social conservative, Rep. Charles H. Taylor (R-N.C.), who did little to disguise his disdain for the District. Taylor once suggested, for example, that investing in new D.C. computers was like "throwing money down a rat hole."

Taylor and his predecessor, Rep. James T. Walsh (R-N.Y.), both routinely called for drastic cuts in D.C. budgets and often backed contentious proposals that would have forced fundamental changes in city policies, such as an eventually defeated plan to use government money to send students to private schools.

The conventional wisdom among city officials was that Istook would be even more heavy-handed. This was an Oklahoman who, when running for Congress in 1992, suggested that convicted felons be tattooed to ensure that they could not buy guns. Upon arrival in Washington in 1993, he led the fight to bar the city from extending health benefits to domestic partners, calling the program "the equivalent of gay marriage." That same year, he vowed not to hire homosexuals, noting that "I don't think that someone who is an open, practicing homosexual would be comfortable with the political agenda in my office."

Istook's reputation as a "right-wing warrior," as he was dubbed, only broadened as the years passed. A 1995 proposal by Istook would have allowed states to prohibit funding for abortions for poor women who were victims of rape or incest. In 1997, he led the GOP bid to require teenage girls to get parental consent before receiving contraception. And last year, he led an unsuccessful drive to permit school prayer and religious displays in federal buildings.

"The kinds of wedge issues which have stalled or killed D.C. appropriations bills in the past are those issues he is most likely to be the sponsor of," Moran predicted after Istook became chairman. Added Williams: "There was a concern among all of us."

But from the start, Istook surprised the skeptics, inviting Norton and Williams to meet with him, the House speaker and other House leaders. He vowed "to do a lot of listening and a lot of homework."

The former radio news reporter and father of five--who saves money and time by sleeping on the leather couch in his Capitol Hill office, rather than renting an apartment--took a crash course in city affairs. He toured schools, public housing complexes and the much-maligned Department of Consumer and Regulatory Affairs. He went on patrol with police.

Istook developed a particular interest in the D.C. agency that supervises the city's 30,000 people on parole or probation or awaiting trail. Only about 4 percent of the parolees are subject to drug testing, though an estimated 3,000 are addicts. To feed their habits, city officials told Istook, these drug-addicted convicts commit tens of thousands of crimes each year. Istook visited the Court Services and Offender Supervision Agency's drug-testing lab, talking strategies with the staff.

"He seemed to be persuaded by what we think is a major problem: the lack of adequate funding for drug testing and treatment," said Court Services trustee John A. Carver III.

When it came time for the House Appropriations subcommittee to mark up the District budget last month, Istook proposed adding $25 million to the Court Services budget for random drug testing, expanded drug treatment and 125 new court officers and other staff to crack down on misconduct.

"This will be the largest program of its kind of any city in the United States," he said on the House floor.

Several of the other provisions Istook's committee added to the budget bill reflect talks he and other House members had with D.C. officials, such as an extra $20 million to trim the city work force by allowing Williams to offer severance packages to 1,000 employees, $8.5 million to accelerate the movement of 3,200 D.C. foster-care children into adoptive homes and $5 million to help clean the Anacostia River.

Istook hinted in late June that he might add language to the budget bill to require the District to enact its five-year, $300 million package of tax cuts even if the economy faltered. But Williams and other city officials convinced him that the required spending cuts might be too severe. So instead, Istook included language in the budget bill that allows revisions in the tax plan without congressional approval.

"He really gave us the opportunity to put our numbers on the table, make our points," D.C. Chief Financial Officer Valerie Holt said. "And the results are positive."

The District-Congress detente extends beyond Istook and his committee. After two years of budget surpluses, the city continues to recover from its near-collapse of the mid-1990s. Williams's effort to remake D.C. government also has won kudos on Capitol Hill. Istook said that's why he was willing to give city officials a bit more deference than the Constitution requires.

"I know they are making a concerted effort to clear up a backlog of inherited problems," Istook said. "I try to be as respectful as can be of their priorities."

Williams has praised Istook, saying that "he is taking his oversight role seriously, and I think he is managing it very effectively and responsibly." But like others, Williams expressed frustration that Istook and other Republicans maintained riders banning city spending on abortions or needle exchange, the latter of which is aimed at preventing the spread of the HIV infection that causes AIDS.

The House on Thursday also added--and Istook backed--an amendment to prohibit the city from legalizing marijuana, even if voters approved a 1998 initiative calling for its legalization to treat certain medical conditions. (Congress last year blocked the city from tabulating the results of that vote.) But even when it came to the riders, Istook showed a willingness to compromise.

After several Democrats--and some Republicans--condemned a measure that would keep the city from spending local money on a lawsuit seeking to establish voting rights in Congress for the District, Istook suddenly modified his stand. He announced on the floor last Thursday that in a House-Senate conference committee this week, he will try to amend the provision so that the city can pay lawyers working the case in the next year.

The D.C. budget eventually passed the House on a 333 to 92 vote, compared with several recent years when margins were at times only a few votes.

The relationship between Istook and city officials has become so cozy that several are involved in an event that would have been inconceivable a year ago: a fund-raiser for the chairman of the Republican-led House Appropriations panel on the District.

Council member David Catania (R-At Large), who is openly gay, and council member Carol Schwartz (R-At Large), an ally of the gay community, are the honorary co-chairmen of the event Thursday at a downtown restaurant. Democrats Williams and Cropp are listed on the invitation as "special guests." Some city officials, while appreciative of Istook's restraint this year, say the lovefest may have gone too far.

"Let's not forget the totality of [Istook's] points of view, which include homophobic and antiabortion stands," said council member Jim Graham (D-Ward 1), who also is openly gay. "This is a very conservative Republican who has an agenda that, generally speaking, is out of step with the prevailing views of this city. I don't want that to be lost."