When the new Democratic Congress tries to rein in the expanded powers claimed by President Bush, it faces one formidable obstacle: Vice President Dick Cheney.

In 1987, as a U.S. representative from Wyoming, he was vice-chairman of a joint committee that investigated whether the Reagan administration had illegally ignored a law barring the CIA from supporting the rebel Nicaraguan Contras. Instead, the Reagan administration secretly sold arms to Iran and funneled the proceeds to the Contras.

Mr. Cheney refused to sign the blistering committee report. He wrote a minority report insisting that the White House had made “mistakes in judgment and nothing more.” It declared that the president is “the country’s exclusive foreign policy leader.” Some presidential scholars disagree and say the power is shared with Congress.

The Boston Globe’s Charlie Savage cited that incident in a recent account of Mr. Cheney’s “mission to expand – or ‘restore’ – the powers of the presidency.”

In 1974, when Congress was preparing to investigate a New York Times article by Seymour Hersh on CIA domestic spying on Vietnam war protesters, Mr. Cheney urged creation of a presidential commission to investigate the CIA. Mr. Savage obtained a Cheney memo to President Ford saying that the proposal was “the best prospect for heading off congressional efforts to further encroach on the executive branch.”

Another memo urged indicting Mr. Hersh under the 1917 Espionage Act to “create an environment” that might intimidate both the press and Congress.

As defense secretary, under the 1917 Espionage Act, Mr. Cheney advised the first George Bush to launch the Gulf War without consulting Congress. Mr. Bush rejected the advice and won a bare majority vote. Mr. Cheney said afterward, “From a constitutional standpoint, we had all the authority we needed. If we’d lost the vote in Congress, I would certainly have recommended to the president that we go forward anyway.”

As vice-president, Mr. Cheney has held to the same hard line on presidential power. He said: “In 34 years, I have repeatedly seen an erosion of the powers and the ability of the president of the United States to do his job. I feel an obligation . . . to pass on our offices in better shape than we found them to our successors.”

One of his first acts was to convene a committee to formulate an energy policy. He fought successfully to keep its membership and actions secret.

After the Sept. 11 attacks, he and his staff led the way in invoking the president’s “inherent” authority to issue secret orders authorizing aggressive interrogation of prisoners, secretly wiretapping phone calls without court warrant, and kidnapping suspects and sending them abroad for torture in a chain of secret prisons.

Mr. Cheney, long considered a major power in the administration, has lost some leverage with the indictment and resignation of his deputy, Lewis “Scooter” Libby, and the retirement of his longtime political partner, Defense Secretary Donald Rumsfeld.

But he remains a shrewd, determined advocate of a strong presidency, virtually unbound by any congressional restrictions.