WASHINGTON — A White House proposal asking Congress to authorize military tribunals for suspected terrorists will face opposition from Republican senators who have been working on a tribunal plan of their own.

President Bush acknowledged yesterday that America has been operating secret prisons for Al Qaeda operatives. He said he is closing the secret facilities and transferring 14 male prisoners, including the mastermind of the terrorist attacks of September 11, 2001, Khalid Sheikh Muhammad, to Guantanamo Bay.

In a close election year, Mr. Bush framed his proposal as a challenge to bring the perpetrators of the attacks to justice. “As soon as Congress acts to authorize the military commissions I have proposed, the men our intelligence officials believe orchestrated the deaths of nearly 3,000 Americans on September 11, 2001, can face justice.”

The legislation became necessary after the Supreme Court ruled that the old tribunal systems violated the Constitution and international law. In June, the court ruled that the military trial for Osama bin Laden’s bodyguard, Salim Ahmed Hamdan, was unconstitutional because the military courts were not created with the consent of Congress and violated the Geneva Conventions for prisoners of war.

The Supreme Court ruling in Hamdan v. Rumsfeld prompted the Senate Armed Services Committee to begin drafting its own legislation, which differs substantially from the White House plan.

A spokesman for the committee, John Ulyot, said yesterday that its bill will have stricter standards for the treatment of hearsay and secret evidence that prosecutors could introduce.

“[Chairman] Senator Warner is confident the Senate will produce a bill by the end of the month. Whether the starting point is the admin or his own bill, the differences between the bills will be sorted out through the amendment process. The disagreements will be resolved through that normal process,” Mr. Ulyot said.

However, other senators who have been working on the legislation were clearer in their opposition to the president. “I think it’s important that we stand by 200 years of legal precedents concerning classified information because the defendant should have a right to know what evidence is being used,” Senator McCain, a Republican of Arizona, said. The senator helped draft the amendment last year that formally outlawed the torture of detainees by the military.

Another senator who has been working on the tribunals proposal, Lindsey Graham, a Republican of South Carolina, said, “I believe what differences we may have between the current Bush administration proposal and the Senate Armed Services Committee draft proposal can be overcome and that agreement will soon be reached.”

One Republican strategist who was briefed yesterday by the White House before the president’s speech said he thought the differences between the three senators and the White House are significant. “The president has a solution on this, but John McCain and Lindsey Graham are against the proposal,” Grover Norquist, who is the president of Americans for Tax Reform, said.

Mr. Norquist said he thinks the president’s proposal makes for good strategy as well as good policy. “The president very wisely focused attention away from how to run a trial and treat detainees in the speech. Now it’s, ‘We want a trial. Let’s come up with some reasonable rules to punish people who did this to us.’ All of this highlights the war on terror, not the occupation of Iraq. These are the things we know the American people do not think the Democrats are serious about,” he said.

So far, Democratic leaders in the House and Senate have said they welcome the president’s suggestion that Congress authorize the tribunals. But the Senate minority leader, Harry Reid, a Democrat of Nevada, said he supports the Senate process.

“The Supreme Court has said Congress should establish the rules for military commissions,” Mr. Reid said. “To meet this challenge, the Armed Services Committee is drafting a bipartisan proposal that reflects the views of our senior uniformed military lawyers. Senator Frist must allow that process to move forward. The last thing we need is a repeat of the arrogant, go-it-alone behavior that has jeopardized and delayed efforts to bring these terrorists to justice for five years.”

The top Democrat in the House, Rep. Nancy Pelosi of California, said the president’s refusal to ask Congress to authorize the tribunals has delayed justice for the suspected Al Qaeda terrorists. A senior fellow at the more hawkish Democratic Leadership Council who once advised Mr. McCain, Marshall Wittmann, said he expects that his new party will not block the president’s tribunal proposal.

“Democrats should not take the bait. They cannot appear to be any less aggressive than the Republicans in attacking terrorism. So they would be best served by taking a pass on this issue, and passing it and moving on. If they put up a strenuous objection to the president’s proposal, they will be playing into the hands of Karl Rove. I think saner heads in the Democratic Party will prevail,” he said.