By Alister Bull
WASHINGTON (Reuters) - President Barack Obama, facing criticism from some lawmakers that U.S. military action against Libyan leader Muammar Gaddafi is about to become illegal, said on Friday the mission would benefit from congressional support.
Obama did not explicitly ask Congress to authorize the action he ordered in March to protect Libyan civilians, as his critics say is demanded by the 1973 U.S. War Powers Act.
Instead, he suggested U.S. involvement in Libya was now so limited that Congress's authority was not needed.
"I wish to express my support for the bipartisan resolution ... which would confirm that the Congress supports the U.S. mission in Libya and that both branches are united in their commitment," the president said in a letter to top lawmakers.
"It has always been my view that it is better to take military action, even in limited actions such as this, with Congressional engagement, consultation, and support."
Obama notified Congress on March 21 he had ordered military action against Libya as part of a multinational coalition.
That made Friday the 60-day deadline to seek congressional authority for the action under the War Powers Act. But the White House indicated it did not view the current level of U.S. military involvement in Libya as reaching that threshold.
"This is a narrow U.S. effort that's intermittent and is principally to support the ongoing NATO-led and U.N. authorized mission," a White House official said. "The U.S. role is also not only one of support but the kinetic pieces of that effort are intermittent."
The Senate last month blocked a vote on a proposal by Rand Paul, a first-term Republican senator and a favorite of the conservative Tea Party movement, to reaffirm the constitutional authority of Congress to declare war.
Paul's amendment quoted then-Senator Obama's words from 2007, when he told the Boston Globe "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."
Since March, NATO allies including France, Britain and the United States have conducted a campaign of air strikes to shield civilians from Gaddafi's forces.
Obama, who has ruled out putting U.S. troops on the ground in Libya, said on Thursday it was inevitable that Gaddafi would have to leave power.
In the letter to lawmakers, the president said NATO was now taking the lead against Gaddafi loyalists but that U.S. involvement remained critical to protecting Libyan civilians.
He also said congressional action to support the mission would be a valuable illustration of U.S. commitment, while nodding toward the constitutional issue raised by the 60-day War Powers Act deadline.
"Such a resolution is also important in the context of our constitutional framework, as it would demonstrate a unity of purpose among the political branches on this important national security matter," Obama said.
(Editing by John O'Callaghan)