Days after Amtrak's board of directors fired the railroad's president, the chairman of the House subcommittee that oversees Amtrak said Tuesday that the board might have acted illegally because it lacked a quorum.

Yet the chairman of the panel, Representative Steven C. LaTourette, Republican of Ohio, was among the mildest of the critics at a hearing that ran more than two and a half hours. A parade of Republicans and Democrats denounced the board for firing the president, David L. Gunn, who had earned widespread praise for stabilizing Amtrak's operations.

Amtrak's board chairman and the Transportation Department's representatives on the board sat stoically through the hearing. Places were set for two other members of the board, but they did not appear.

The unpopular move by the directors has focused attention on their legal status. Mr. LaTourette, head of the railroad subcommittee of the House transportation panel, said the board had apparently not had a quorum in the last few years. He said that under the board's bylaws, a quorum would be five of seven directors. The board has only four directors, and two of those will lose their seats when Congress recesses for the year in a few weeks.

The Transportation Department's chief counsel, Jeffrey A. Rosen, who also serves on the Amtrak board as the representative of the transportation secretary, disputed Mr. LaTourette on that point and others. But others at the hearing, some seeking to reinstate Mr. Gunn, seized on the procedural questions surrounding the board.

"You've opened up a whole Pandora's box," said Eleanor Holmes Norton, the District of Columbia's delegate to the House and a member of the transportation committee, addressing David M. Laney, the board chairman.

Ms. Norton described the board's uncertain legal status as "a lawsuit waiting to happen."

Senator Charles E. Schumer, Democrat of New York, said he had written to the White House to recommend that Mr. Gunn be reinstated until lawyers could determine the status of the directors. "There is no clear legal consensus that the board had the power to fire Mr. Gunn," Mr. Schumer testified.

Senator Frank R. Lautenberg, Democrat of New Jersey, linked the firing of Mr. Gunn to a bill recently approved by the Senate, on a 93 to 6 vote, that would authorize a multiyear spending package for the railroad, against the Bush administration's wishes. Mr. Lautenberg, who sponsored the bill with Senator Trent Lott, Republican of Mississippi, said the board had fired Mr. Gunn as "retribution for our misbehavior."

Mr. Laney and Mr. Rosen, the only board members who have spoken publicly, have said Amtrak should not expect annual subsidies from Congress forever. That idea was supported by only one committee member, Representative John Mica, Republican of Florida.

Exactly why Mr. Gunn was fired after three and a half years on the job was not completely clear. Mr. Gunn said it was because he had opposed the board's preliminary moves to strip Amtrak of the tracks in the Northeast Corridor, from Washington through New York to Boston.

Mr. Laney denied that that was the board's intention. He said Mr. Gunn had lost enthusiasm for contracting out food service and train maintenance, adding that those steps would cut losses and were part of a strategic plan approved by the board in April. Mr. Gunn said he had worked hard to help write that plan and was deeply involved in carrying out parts of it that the railroad could accomplish on its own.

Mr. Laney acknowledged that the board had hired an outside public relations firm to announce that Mr. Gunn was being fired. Mr. LaTourette said Amtrak was obligated by law to tell Congress about the hiring of the firm because it was a form of lobbying Congress.