A leading Republican lawmaker urged President Bush on Sunday to underpin any military action against Iraq with resolutions from the United Nations, demanding that weapons inspectors be allowed to return, and from Congress, giving its approval for action.

Sen. Richard Lugar, a senior member of the Senate Foreign Relations Committee, said the U.N. Security Council's action would be little more than symbolic, because Iraq would reject the demand and it would be left to the Americans to enforce it.

Just before Lugar spoke in a broadcast interview, Iraq's deputy prime minister, Tariq Aziz, interviewed from Baghdad, said the idea of the inspectors' return is "a nonstarter because it's not going to bring about a conclusion."

"By saying they're not even going to start, [Aziz] gives us the opportunity [to] go back to the U.N. to re-energize our partners, to indicate how unreasonable the Iraqis are, to get resolutions that if we cannot get in -- and apparently we're going to have difficulty doing that -- then we have a military force option," Lugar said.

Lugar, R-Ind., was among the earliest Republican leaders to advocate caution by Bush as he contemplates how to deal with what the administration says is President Saddam Hussein's quest for chemical, biological and nuclear weapons of mass destruction. The administration has made "regime change" in Iraq a basic goal of its foreign policy.

To end the 1991 Persian Gulf War, Iraq agreed to cease all attempts to obtain such weapons and to allow unrestricted inspections to ensure compliance. Inspectors left in late 1998, just before punitive U.S.-British airstrikes because of Iraq's refusal to cooperate, and Saddam refused to allow the inspectors back in.

Policy on whether to seek renewed weapons inspections after a four-year hiatus or to strike Iraq pre-emptively to remove Saddam has become muddied. Last week, Vice President Dick Cheney said inspectors "would provide no assurance whatsoever" of compliance and might even bring "false comfort" that Saddam had been contained.

On Sunday, the British Broadcasting Corp. released a text of an interview in which Secretary of State Colin Powell said, "The president has been clear that he believes weapons inspectors should return."

Aboard Air Force One on Sunday, as Bush flew back to Washington from a month's vacation in Texas, White House spokesman Scott McClellan said Bush agrees that "unfettered inspections" are a required first step toward solving the Iraq problem, but not necessarily enough.

Inspections are "no guarantee if at the same time the regime in Iraq continues to try to hide weapons of mass destruction," McClellan said. The burden is on Iraq, he said, to prove the country is not producing weapons of mass destruction.

Another Republican senator, Fred Thompson of Tennessee, a member of the Senate intelligence committee, said he sees no reason to even bother with trying to send back the inspectors.

"I think Saddam will not allow inspectors back in, number one. The Security Council will not support us to put inspectors back in, two. And three, if inspectors went back in, it would be a fool's errand," Thompson said on NBC's Meet the Press.

In testimony a few months ago, Thompson said: "These same former inspectors ... said that there's no way that you can discover and determine what he has. It's too large a country, there are too many facilities. He is a past master, and even better now than he was then, on hiding facilities. And once you get close, he shuts you down."

Lugar's push for congressional votes on any military involvement drew other prominent support Sunday. Writing in Monday's edition of Time magazine, Sen. John McCain, R-Ariz., Bush's principal opponent for the 2000 GOP nomination, said he remains unconvinced "that the large U.S. force contemplated for the operation is the best or only option" to oust Saddam.

McCain said, however, that Bush "should seek congressional support soon -- before staging large numbers of troops in advance of hostilities. Although the legal necessity for doing so is arguable, the political imperative is not."

"Public support, best measured by the extent of congressional support the president receives, is as important as the size and quality of our military force," McCain wrote.

Writing in Sunday's edition of The Washington Post, former Sen. Bob Dole, R-Kan., the Republican presidential nominee in 1996, agreed that Bush has the authority needed to send troops without Congress' say-so, but "when all is said and done, Congress will respond affirmatively and the president will be strengthened as he reaches out to willing allies. Saddam Hussein will also clearly understand that America means business."