But the criticism keeps coming. After his tense radio interview—which contained echoes of the O’Reilly episode—Frank, sitting in the front passenger seat of his S.U.V., continues to stew: He was sure that Adam Bond, the radio host, had been fed his information by conservative blogs. He was certain that Grover Norquist, a tax-hating, fiery-mouthed G.O.P. operative, was behind it. Norquist, he says, is the one telling Republicans to bring up his name in connection with Fannie Mae whenever possible.

Later, I call Norquist. He reciprocates Frank’s hostility. “He’s our No. 1 enemy,” declares Norquist, whose antitax lobbying group, Americans for Tax Reform, has long been a thorn in the side of Democrats. “He’s responsible for something that dwarfs Enron.”

Norquist laughs off suggestions of other motives. “This is a guy who’s never made a mistake in his life, and everything is because we’re homophobic,” he says.

Frank’s relations with others in Washington, both on the left and right, are more complicated. Amid the cascading series of financial failures in the fall, Frank, oddly enough, found his most productive working relationship to be with Treasury Secretary Paulson, a wealthy former Goldman Sachs chairman. For his part, Paulson became far more comfortable dealing with Frank than with his fellow Republicans in Congress.

The two men consulted on a daily basis during critical periods of the crisis, sometimes face-to-face, more often in impromptu phone calls. They communicate very differently: Paulson sometimes descends into halting jargon, while Frank can cram three sentence fragments into one breath. But a trusting relationship was formed. When Paulson said he needed $700 billion, it was Frank who expended the mighty effort to persuade resistant House Democrats. When President Bush called an emergency White House meeting, to be attended by both presidential candidates, it was Frank who peppered the president’s aides with detailed queries about the proposed bailout plan.

“When I talk to him about the markets, I know he immediately gets it,” Paulson told me at the height of the crisis. “And he has been consistently right in the advice he has given me about politics.”

The two reached a level of comfort with each other that allowed them to dispense with formalities. Just after the House passed the bailout package, Frank’s cell phone rang during a briefing to the press. “I’ll call him back,” he barked and snapped it shut.

“Was that the president?” a reporter joked.

“No,” Frank replied, in all seriousness. “It was the secretary of the Treasury.”

But as the crisis continued to unfold and Paulson pushed to broaden government aid to more industries and companies, the relationship became strained. Frank saw Paulson sinking money into an ever-widening pool of private interests—corporate lenders, credit-card companies, the hemorrhaging insurance firm A.I.G.—while resisting even a relatively modest effort to provide relief to indebted homeowners or failing automakers, two constituencies important to congressional Democrats. At the same time, the press was full of reports that big banks were simply holding on to their shares of the $700 billion or planning to use the money to acquire smaller banks.

After John Thain, the C.E.O. of Merrill Lynch, publicly referred to the bailout money as a “cushion”—implying that the firm was going to sit on it rather than lend it—an incensed Frank, who called it “infuriating,” phoned Paulson to complain.

“He said, ‘I agree with you. I’ve privately criticized him,’ ” Frank recalls. “I said, ‘Well, you’ve got to do it publicly’—which he has not.” (A Merrill Lynch spokesman declined to comment. The firm won’t receive federal aid until it completes its merger with Bank of America.)

Frank is already close with Paulson’s successor, Tim Geithner, whom Frank has known since the Clinton administration, when Geithner was at Treasury and the two collaborated on issues related to the World Bank. When the Fed sponsored an event to honor its gay employees, Frank and Geithner both attended. Frank keeps a picture on his desk of the two of them at the ceremony.

But Frank’s relationship with the new president is still largely uncharted. He supported Hillary Clinton in the primaries and was initially dubious about what he called Obama’s “very labored authenticity.” Since then, he says he has come to appreciate the new president’s calm and thoughtfulness. During the transition period, however, Frank expressed concern to me that Obama’s deliberate style was doing harm, and he went so far as to invoke the precedent of Herbert Hoover’s disastrous handover to Roosevelt. “I am a little troubled,” he said in early December. “Damage is being done by the fact that nothing is being decided.”

Meanwhile, Frank was also encountering disenchantment on his left, and by mid-December, signs of internal party dissent had burst into the open. During a contentious hearing that month on the subject of oversight of the bailout, Democratic members of Frank’s committee complained that they’d been “bamboozled,” asked why Frank had not yet called any bank C.E.O.’s before the committee to defend their management of the federal funding, and wondered aloud whether “Goldman Sachs is running this country.” Maxine Waters, a liberal Democratic congresswoman from California, took on the chairman directly. “I appreciate everything that you have done, but I’m not going to even cooperate with you anymore,” she said, staring down Frank. “You’ve been too kind, you’ve been too good, and you have allowed them to walk all over us.”

As she yielded the floor, Waters laughed nervously and braced herself for the response. “Please do not use your microphone,” she implored him.

Frank glared at her. “The gentlewoman,” he said, “does not have to worry about much further communication between us.”