The Senate Judiciary Committee chairman, Arlen Specter, said he would seek to subpoena witnesses if he isn’t satisfied the Bush administration is cooperating with the panel’s review of America’s domestic surveillance program. The committee has sought information about the eavesdropping on phone calls involving suspected terrorists without court warrants. President Bush ordered the National Security Agency to initiate the surveillance program after the terrorist attacks on September 11, 2001.

Mr. Specter, a Pennsylvania Republican, has proposed legislation to provide for court review of the constitutionality of the surveillance program. The senator said that, while he is encouraged by recent talks with Vice President Cheney, many questions still need answers on how the administration views the legislation. “If we don’t get some results, I’m prepared to go back to demand hearings and issue subpoenas as necessary,” Mr. Specter said yesterday on CNN’s “Late Edition.”

Mr. Cheney this week offered no apologies to Mr. Specter after the senator complained that the vice president went behind his back to interfere with the Judiciary Committee. Mr. Cheney defended his actions in lobbying several Republican panel members to deflect the committee’s request for information on the electronic surveillance program.

The lobbying led Mr. Specter to postpone summoning three telephone company executives to testify about whether they furnished billions of call records to the government. Mr. Specter said there was no point in calling the executives because the Bush administration instructed them not to provide any classified information.