As the country debates the wisdom of going to war against Iraq, President Bush and Congress are circling each other in a long-running but unresolved constitutional clash of wills over who gets to make that call.

The Constitution provides that Congress has the power "to declare war." But it also makes the president the commander in chief of the armed forces and gives him broad authority as the national executive.

The threat of war in the Persian Gulf has raised anew the issue -- last hotly debated during the never-declared war in Vietnam -- of how the authors of the Constitution intended those provisions to interact, and how the Constitution applies in a modern age the framers may never have envisioned, of far-off wars waged by a world power.

Defense Secretary Richard B. Cheney told the Senate Armed Services Committee last week that Bush needs no "additional authorization from the Congress before committing U.S. forces to achieve our objectives in the gulf."

With equal conviction, some congressional leaders assert that if Bush wants to take the country into war, the Constitution provides in "clear, explicit and unmistakeable" terms that he must obtain congressional approval, as Senate Majority Leader George J. Mitchell (D-Maine) said last month.

"Our firm view is that the president has no legal authority, none whatsoever, to commit American troops to war in the Persian Gulf or anywhere else" without congressional authorization, Mitchell said.

The debate is nearly as old as the Republic and not likely to end. Yesterday, federal judges here dismissed two lawsuits that raised the question -- one by 54 members of Congress, and another by a reservist protesting being sent to the gulf.

While the cases will likely be appealed, courts are reluctant to intervene in such disputes between Congress and the president. The issue is largely a test of political will between the two branches, each armed with differing views of the same information: the words of the Constitution, varying interpretations of the intent of those who wrote and ratified it, and the course of U.S. history since then.

The discussion of the congressional war power -- Article I, Section 8, Clause 11 -- takes up less than two pages of 1,273 pages of records of the constitutional convention. Meeting behind closed doors in Philadelphia on Aug. 17, 1787, the authors of the Constitution discussed a draft resolution giving Congress the power to "make war."

Charles Pinckney of South Carolina argued that the legislature as a whole was too cumbersome to wield the war power and suggested placing it in the smaller Senate.

His fellow South Carolinian, Pierce Butler, proposed instead that war-making power be lodged with the president, "who will not make war but when the nation will support it." That drew a rebuke from Elbridge Gerry of Massachusetts, who told his colleague he "never expected to hear in a republic a motion to empower the Executive alone to declare war." Butler's motion did not get a second.

James Madison and Gerry then moved to change the word "make" to "declare," according to Madison's notes, "leaving to the Executive the power to repel sudden attacks."

As the states debated ratifying the document, James Wilson, one of its primary drafters, described the purpose of the clause to the Pennsylvania ratifying convention: "This system will not hurry us into war; it is calculated to guard against it. It will not be in the power of a single man, or a single body of men, to involve us in such distress. . . . "

Backers of congressional power point to these debates as support for their position. "The discussions at the constitutional convention clearly suggest that the framers intended to give to Congress the exclusive authority to determine the policy question of whether or not to go to war," said Duke University law professor Walter Dellinger.

While the commander-in-chief clause gives the president the power to "supervise the conduct of military operations," he said, it "does not confer upon the president the authority to decide the profound policy question" of whether to launch war.

Proponents of executive authority say the issue is not so clear. For one thing, they note that the change of the wording of congressional power, from "make" to "declare," was clearly intended to give the president more latitude.

Presidential backers argue that the framers, knowing of the problems caused by the Continental Congress's interference with Gen. George Washington's operations during the Revolutionary War, intentionally created an executive with great power in military affairs.

"There's evidence for everything in the debates" of the framers, said Assistant Attorney General Stuart M. Gerson, who argued against the lawmakers' suit at a court hearing last week, emphasizing the administration's view that courts have no business in such interbranch disputes. "What you can say is that different people who voted on the Constitution had different motivations."

Those who say the Constitution gives the president broad authority say that, to the framers, a declaration of war was a formal step that had grave consequences under both domestic and international law, and one for which they wanted congressional approval. But, they argue, the framers envisioned other situations in which the country would want to engage in hostilities -- a "small 'W' war" -- without the legal consequences of an officially declared war, and did not mean to tie the president's hands in such circumstances.

The Justice Department's Gerson notes as well that while the Constitution talks about a declaration of war, "it doesn't say when" one is required -- before or after the initiation of hostilities.

Others say the history and structure of the Constitution make clear that the framers were concerned about giving one person the power to embroil the country in large-scale hostilities, and wanted Congress to make that grave decision before the fact -- not necessarily through a formal declaration of war but by some affirmative authorization.

Yale Law School professor Harold H. Koh pointed out that the War Powers Clause also vests in Congress the exclusive right to grant "letters of marque and reprisal" -- archaic documents giving private parties the right to seize enemy ships. That, he said, illustrates that the framers envisioned "gradations of uses of force" and wanted Congress to "play a triggering mechanism" with all of them -- with the exception of the president's ability to act in emergency situations to repel attacks.

"The principle underlying it is that it's Congress that's supposed to authorize uses of force up to and including war," said Koh, who helped write a friend-of-the-court brief in support of the lawmakers. "The crucial idea is the sharing of power" between Congress and the president.

In arguing for congressional or executive power, both sides invoke history as well. Calling on the court to dismiss the lawmakers' suit, the Justice Department noted that "U.S. armed forces have acted without a declaration of war in scores of instances from the presidency of John Adams to the present," from minor incursions to large-scale conflicts like those in Korea and Vietnam.

"If you're arguing that the declaration clause means Congress has the exclusive power to decide to go to war or to cause war in international relations you're just whistling Dixie," said Abraham D. Sofaer, State Department legal adviser under President Ronald Reagan.

Sofaer noted -- as did Cheney in his testimony last week -- that there have been more than 200 situations in which U.S. troops have been involved in hostilities, only five of which involved formal declarations of war: the War of 1812, the Mexican War, the Spanish-American War, and World Wars I and II.

With the hostages freed, Sofaer said, the president needs congressional approval to "act in the collective self-defense of Kuwait" -- but that approval need not be formal and could even be inferred in some cases from congressional silence.

Responding to the historical argument, Dellinger said that "every real war the United States has ever engaged in was declared or authorized by Congress up through and including World War II."

He said the "troublesome cases" are Korea, where President Harry S. Truman sent troops to repel the invasion of South Korea and never obtained subsequent congressional authorization for the ensuing "police action," and Vietnam. He said Congress arguably authorized the latter in the 1964 Gulf of Tonkin Resolution, and that an unconstitutional action in Korea would not legitimize later encroachments on congressional power.

"Whatever the framers meant by war it included half a million troops facing each other across a battle line," said Dellinger. "If the declaration of war clause does not apply here it will have been stripped out of the Constitution."