By Susan Cornwell
WASHINGTON (Reuters) - Tensions over the U.S. military intervention in Libya are vexing Congress.
While some lawmakers back the action against Muammar Gaddafi's forces, others say President Barack Obama should have formally consulted them before getting involved.
Here are some answers to questions about the concerns of Congress and its relative powers versus the presidency in U.S. military actions:
WHY ARE SOME LAWMAKERS UPSET WITH OBAMA OVER LIBYA?
Many liberals in Obama's Democratic Party oppose a third war in the Muslim world on top of the U.S. troop commitments to Iraq and Afghanistan, which they have long sought to end. Partly because the other two wars have dragged on for years (since 2001 in Afghanistan and 2003 in Iraq), these lawmakers find it hard to believe Libya will be a limited engagement.
Republican leaders in the House of Representatives say the Democratic Obama administration did not adequately explain the Libya mission or seriously consult with lawmakers about it before the U.S. cruise missiles started to fly last weekend.
Some in both parties have said that the U.S. government, with its $1.4 trillion deficit, can't afford another war and has no particular security interests in Libya anyway.
Lawmakers like Republican Senator Richard Lugar say there should have been a full congressional debate and vote on a declaration of war. Moderate Democratic Senator Jim Webb told MSNBC that Congress has "been sort of on auto-pilot" and "this isn't the way that our system is supposed to work".
WHAT ARE THE WAR POWERS OF CONGRESS AND THE PRESIDENT?
Article 1 of the U.S. Constitution says Congress has the power to declare war.
But Article 2 says the president is "Commander in Chief" of the armed forces.
This has been a source of friction between the two branches at least since President Harry S. Truman committed U.S. forces to Korea in 1950 without congressional approval.
"No president has officially recognized Congress' right to vote on all military actions. As commander in chief, presidents reserve the right to deploy forces without congressional approval" said Henry Nau, professor of political science at George Washington University.
In 1973 Congress sought to clarify things by passing the War Powers Resolution requiring the president to notify Congress within 48 hours of committing forces to military action. Obama did this by sending a letter to Congress on Monday about the Libya intervention.
The 1973 law also prohibits U.S. armed forces from being involved over 60 days without congressional authorization.
But the constitutionality of the War Powers Resolution has been questioned, and how it is interpreted may depend on whether one is a president or a lawmaker.
In 2007 then-Senator Obama told the Boston Globe that "the president does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the (U.S.) nation."
ARE THERE PRECEDENTS FOR OBAMA'S LIBYA ACTION?
Now that he is president, "Obama is following a long historical precedent" by not seeking a vote of Congress ahead of the Libya intervention, said Sarah Kreps, an assistant professor of government at Cornell University.
"Iraq and Afghanistan, which did have congressional authorization, were actually unusual compared with many interventions of the 1990s that Congress did not authorize," she said.
She listed as examples George H.W. Bush's intervention in Somalia in 1992; Bill Clinton's sending troops into Haiti in 1994; Clinton's firing of cruise missiles at a camp in Afghanistan in a failed attempt to hit al Qaeda leader Osama bin Laden in 1998; and Clinton's bombing of Kosovo in 1999.
CAN CONGRESS MOVE TO STOP THE INTERVENTION? WILL IT?
The Senate's Assistant Majority Leader Richard Durbin, who supports Obama's Libya move, said on Wednesday that under the War Powers Resolution, "any senator can ask to call this question, as to whether we support the actions of the president."
But Durbin said he did not know if anyone would do this when Congress, which is on recess, returns to work next week.
Another route would be for Congress to try and use its "power of the purse" to cut off funds for the Libya operation.
Representative Dennis Kucinich says he'll offer an amendment to an upcoming spending bill that would "de-fund" the Libya action by banning using taxpayer funds to pay for it.
Kreps said that she thinks it is doubtful Congress will actually do anything to stop the U.S. airstrikes. More typically, they issue statements or pass nonbinding resolutions asserting their prerogatives, she said.
"Congress did ultimately pull the plug on funds for Vietnam and of course this brought U.S. involvement to an end, but this is historically rare," Kreps said.
"More common is the Haiti experience (in the 1990s), in which legislators issued symbolic assertions about its power while not actually trying to negate the executive decision that had been made," she said.