Washington - Two former secretaries of state have declared the War Powers Resolution of 1973 obsolete and proposed a new system of closer consultation between the White House and Congress before American forces go into battle.

Their proposal would require the president to consult lawmakers before initiating combat lasting longer than a week except in rare cases requiring emergency action. Congress, for its part, would have 30 days to approve or disapprove of the military action.

The plan would create a new committee of Congressional leaders and relevant committee chairmen, with a full-time staff with access to military and intelligence material. The president would be required to consult with the group in advance of any extended strike.

Secretaries of State Warren Christopher and James A. Baker III oversaw a year-long study of the longstanding tension over war powers between the executive and legislative branches. In a report to be released on Tuesday, they concluded that the 1973 law, which was passed in the waning days of the Vietnam War and which aimed to limit the president's ability to commit American forces to war unilaterally, never served its intended function and must be replaced.

In an Op-Ed article in The New York Times on Tuesday,, Mr. Christopher, who served under former President Bill Clinton, and Mr. Baker, who served under the first President Bush, wrote that the 1973 act is "ineffective at best and unconstitutional at worst. No president has recognized its constitutionality, and Congress has never pressed the issue. Nor has the Supreme Court ever ruled on its constitutionality."

"As a consequence," they wrote, "the 1973 statute has been regularly ignored - a situation that undermines the rule of law, the centerpiece of American democracy."

Presidents since Jefferson have asserted the right to commit troops to battle when they deem it in the national interest. Congress has the power under the constitution to declare war and control spending on military actions, but it has seldom exercised it. The new legislation is designed to clarify when and for how long presidents can act unilaterally.

The question has arisen repeatedly in the context of the Iraq war. In 2002, President Bush sought and received Congressional authorization for military action to enforce United Nations weapons sanction. Since then, however, many members of Congress have claimed that he has exceeded that authority and have tried repeatedly to limit the scope of the war and impose a timetable for withdrawal of troops. All of those efforts have failed.

In 2007, several senators, including Robert C. Byrd of West Virginia, Hillary Rodham Clinton of New York and Barack Obama of Illinois, the likely Democratic presidential nominee, tried to repeal the 2002 war authorization. They also fell short.

In a Republican presidential debate last October, Senator John McCain, the likely Republican presidential candidate, said he would take military action without going to Congress first, "if the situation is that it requires immediate action to ensure the security of the United States of America."

"That's what you take your oath to do when you're inaugurated as president," Mr. McCain said. But he also said that he would seek the approval of Congress if there were time to assess the threat and debate possible courses of action.

Mr. Baker and Mr. Christopher led a commission of former policymakers and constitutional experts to study the war powers question. The group included former Democratic Representative Lee Hamilton, who was a co-chairman with Mr. Baker of the Iraq Study Group in 2006, whose recommendations for a gradual withdrawal from Iraq were largely ignored by President Bush. Other members of the panel were former Republican Senator Slade Gorton of Washington, former Secretary of the Army John O. Marsh Jr., former Attorney General Edwin Meese III and former Deputy Secretary of State Strobe Talbott.