By Steve Holland
WASHINGTON (Reuters) - President Barack Obama is struggling to contain a political backlash over the U.S. military role in Libya and is facing sharp questions over how the United States can extract itself from yet another war.
The president is returning to Washington from Latin America a few hours earlier than planned on Wednesday, needing to tamp down criticism that has mounted during his absence on a five-day foreign tour that began the day U.S. missiles were sent flying into Libya.
Many of the president's fellow Democrats and some Republicans complain they were not properly consulted before the U.S.-led assault on Muammar Gaddafi's forces began and have questioned the legal basis for the conflict.
The lawmakers are demanding answers: What is the precise goal of the mission? How long will it take and how much will it cost? What are the vital U.S. national security interests?
"Call this what they will, we are waging war -- while still engaged in two other fronts -- which will likely require substantial resources over a long period of time," Representative John Larson, chairman of the Democratic caucus in the House of Representatives, said in a commentary on CNN.com.
"The full Congress should have been more informed and involved in this decision."
Each of 161 cruise missiles fired into Libya by Tuesday evening cost $1 million, expensive ordinance to deploy when budget cuts are being negotiated in Washington and Obama is trying to wind down lengthy and costly wars in Iraq and Afghanistan.
"It'll be another disaster. We have to stop spending the treasure of the United States in these military adventures and start taking care of things here at home," liberal Democratic Representative Dennis Kucinich told Fox News.
Obama defended the operation at a San Salvador news conference.
"Events happen around the world in which the United States, with our unique capabilities, has to respond as a leader in the world community," he said.
The uproar appears to have caught the administration off guard and with Obama out of position to offer a sustained counter-argument.
Obama and his aides have sought to assure Americans the U.S. role will be limited in scope and duration, no ground troops will be deployed, and the United States will transfer its lead role to U.S. allies in a matter of days.
But critics question whether the United States can really recede into the background as Obama desires, particularly if Libyan leader Muammar Gaddafi remains in power.
The U.N. resolution for Libya does not demand he leave, and while Obama has said he wants Gaddafi ousted that is not the ostensible goal of military action.
"The president needs to pull together some solution to get us out of this mess," retired General Barry McCaffrey told MSNBC. "What are the political objectives? What are we doing there? What's the endgame?"
Americans so far are going along with Obama. Julia Clark, a pollster at the Ipsos polling firm, said her review of recent polling showed about 50 percent of Americans approve of Obama's handling of the situation.
"If the intervention is short-lived and especially if it's successful, I think it will be a boon to Obama politically," Clark said. "But if it does become a bit of a quagmire, the financial burden very rapidly will be deemed unacceptable."
Americans will be supportive as long as the U.S. role is short, said Democratic strategist Bud Jackson.
"Right now most Americans see this as a limited, well-structured effort hopefully to save lives. If this becomes more protracted, I think the Americans' level of anxiety will go up," he said.
Aides traveling with Obama have insisted in briefing after briefing -- and privately -- that he and his administration consulted widely with Democrats and Republicans before he authorized a U.S. role in the military strikes.
Mindful of the risk of a new foreign entanglement, Obama and his aides believed it was important to stop Libya from becoming a slaughterhouse and avoid a potential repeat of the Bosnian and Rwandan massacres of the 1990s.
"It was a damned if you do, damned if you don't scenario," one member of Obama's traveling delegation said.
(Additional reporting by Matt Spetalnick, Alister Bull and Susan Cornwell, Editing by John Whitesides and Cynthia Osterman)