WASHINGTON » Nearly three weeks after Libya erupted in what may now turn into a protracted civil war, the politics of military intervention to speed the ouster of Moammar Gadhafi grow more complicated by the day — for both the White House and Republicans.

President Barack Obama, appearing Monday morning with Australia’s prime minister, tried to raise the pressure on Gadhafi further by talking about "a range of potential options, including potential military options" against the embattled Libyan leader.

Despite Obama’s statement, interviews with military officials and other administration officials describe a number of risks, some tactical and others political, to U.S. intervention in Libya.

Of most concern to the president himself, one high-level aide said, is the perception that the United States would once again be meddling in the Middle East, where it has overturned many a leader, including Saddam Hussein. Some critics of the United States in the region — as well as some leaders — have already claimed a Western conspiracy is stoking the revolutions that have overtaken the Middle East.

"He keeps reminding us that the best revolutions are completely organic," the senior official said, quoting the president.

At the same time, there are a range of persistent voices — in Congress and even inside the administration — arguing that Obama is moving too slowly. They contend that there is too much concern about perceptions, and that the White House is too squeamish because of Iraq.

Furthermore, they say a military caught up in two difficult wars has exaggerated the risks of imposing a no-fly zone over Libya, the tactic discussed most often.

The U.S. military is also privately skeptical of humanitarian gestures that put the lives of troops at risk for the cause of the moment, while being of only tenuous national interest.

Some of these critics seem motivated by political advantage. Others, including the chairman of the Senate Foreign Relations Committee, John Kerry, who is among Obama’s closest allies, warn of repeating mistakes made in Iraq Kurdistan, Rwanda, and Bosnia and Herzegovina by failing to step in and halt a slaughter.

The most vocal camp, led by Sens. John McCain, the 2008 Republican nominee for president, and Joseph I. Lieberman, the Connecticut independent and another hawk on Libyan intervention, say the central justification for establishing a no-fly zone over Libya is that the rebel leaders are seeking military assistance to end decades of dictatorship.

It is hardly an effort to impose American will in the Muslim world, Lieberman argued in an interview Monday.

"We have to try and help those who are offering an alternative future to Libya," Lieberman said, sounding much like Obama at the White House on Monday. "We cannot allow them to be stifled or stopped by brutal actions of the Libyan government."

But even the critics acknowledge the best outcome would be for the United States not to go it alone, but join other nations or international organizations, in particular NATO, the Arab League or the African Union.

Lieberman and others argue that the risks of waiting may be far greater than the risk of an early, decisive military intervention. He acknowledged that as in Iraq, the United States might unleash an uncertain future of tribal rivalry and chaos, in a country that has no institutions prepared to fill the vacuum if Gadhafi is driven from power.

Yet, he argued: "It’s hard to imagine any new government growing out of this opposition that is worse than Gadhafi."

On television McCain has made similar points, and portrayed Obama as indecisive and weak. But curiously, in a sign of the uncertainties about how the politics of an American intervention would play out, few of the potential nominees for the 2012 Republican presidential ticket have expressed a strong opinion.

For the administration, Kerry’s view is more troublesome, given that he is normally a strong ally on foreign policy issues. He was a fierce critic of the war in Iraq, but he sees Libya as a different matter.

He has pushed the White House to do more — including "cratering" Libya’s airfields so the planes cannot take off.

Kerry, who may be trying to give comfort to officials who want the president to take a stronger stance, said he was pushing the administration to "prepare for all eventualities" and warned that "showing reticence in a huge public way is not the best option."

He added: "What haunts me is the specter of Iraq 1991," when President George H.W. Bush "urged the Shia to rise up, and they did rise up, and tanks and planes were coming at them — and we were nowhere to be seen."

"Tens of thousands were slaughtered," Kerry said.

President Bill Clinton, he said, "missed the chance in Rwanda, and said later it was the greatest regret of his presidency, and then was too slow in Bosnia," where the United States ended up using air power, also in the defense of a Muslim population.

Administration officials make the case that the focus on no-fly zones is overdone. "No-fly zones are more effective against fighters, but they really have limited effect against helicopters or the kinds of ground operations we’ve seen" in Libya, Ivo Daalder, the U.S. ambassador to NATO, said Monday.

He added that "the overall air activity has not been the deciding factor" in fights between rebels and the loyalists and mercenaries surrounding Gadhafi.

It is possible that the mere talk of no-fly zones had some effect. Pentagon and military officials confirmed that sorties by aircraft loyal to the Gadhafi government had dropped by half over the past three days. There was no explanation for the change; it could have to do with maintenance, or a decision to fly helicopters, which are less provocative and harder to track.

The biggest voice of caution has been Defense Secretary Robert M. Gates. It was Gates who laid out last week the strongest case against intervention — a case that even some in the White House say privately they think may have been overstated to make a point about how military actions that look easy can quickly become complicated. Gates forcefully warned Congress during budget testimony that the first act in imposing a no-fly zone would be an attack on Gadhafi’s air defenses, and that the step should only be taken if the United States was ready for a prolonged military operation that could cover all of Libya. He cautioned it might drain resources that are already overstretched in Afghanistan and Iraq, because Libya is such a large territory.

In interviews this week, even some military officials called Gates’ portrayal extreme. Executing a no-fly zone would not require covering the whole country. Most of the Libyan action would be along the coast, where the major cities now held by rebels are. Even so, the opening mission of imposing a no-fly zone would almost certainly include missile attacks on air defense sites of a sovereign nation, which some would indeed regard as an act of war.

Tactical issues aside, Gates is concerned, Pentagon officials say, about the political fallout of the United States attacking yet another Muslim country — even on behalf of a Muslim population. But he is cognizant of the No. 1 lesson of Iraq: that once the United States plays a major role in the ouster of a Middle Eastern leader, it bears responsibility for whatever state emerges in its place.