The Obama administration does not want a long-term U.S. engagement, but it has been criticized domestically for its handling of the war and not reaching out to members of Congress in advance.
The president today reiterated the need for a humanitarian intervention, saying that Gadhafi's threat to raze the eastern Libyan town of Benghazi is what prompted him and coalition partners to act.
The "core principle that has to be upheld here is that when the entire international community also unanimously says that there is a potential humanitarian crisis about to take place, that a leader who has lost his legitimacy, decides to turn his military on his own people, that we simply can't stand by with empty words, that we have to take some action," he said.
Sources told ABC News that Obama was not only alarmed about the potential mass slaughter, but also about the message that would be sent by not stopping it. He was afraid it would say to pro-democracy demonstrators throughout the Arab world that the U.S. has abandoned them and he was also concerned that not acting could further destabilize Libya's neighbors Egypt and Tunisia, still vulnerable after their own revolutions.
The senior White House official told ABC News earlier today that the White House consulted with Congress before any military action began, and will continue to do so. Administration officials for weeks kept members of Congress informed as to how events were developing.
"We take the consultative role very seriously," the official said.
On a practical level, the official said, this was "a fast-moving event that took place when Congress was not in session. In order to stop an imminent humanitarian catastrophe, we had to move very fast, and we still convened a bipartisan congressional meeting."
But both liberal and conservative members of Congress are questioning the intervention at a time when the United States is already engaged in a complicated and bloody battle in Afghanistan, and is confronting major economic issues at home.
While regime change in Libya is the U.S. policy, Gadhafi's removal is not the goal of the operation, and officials say Gadhafi could still stay in power.
The goal is to stop the attacks on civilians and have European and Arab countries enforce a no-fly zone, with the United States moving back to a support role. The United States will continue to squeeze Gadhafi using diplomatic means: travel bans, asset freezes, sanctions.
"There are consequences to removing him militarily," the official said. "It's a far more complicated piece of business and for the military a far more expansive and expensive mission."
But the intervention also raises the question of whether the coalition will intervene in Bahrain and Yemen, where similar uprisings have been brutally squelched.
The difference, White House officials say, is the scope of violence.
"We've condemned the violence in Bahrain and we don't think it's part of any solution to the demonstrations there," the official said. "But in Libya you have Gadhafi carrying out a military campaign against his own people. There was simply a much greater risk of mass killings in places like Benghazi."
Unlike Libya, the United States has close relations with Yemen, and has a major naval base in Bahrain.
The no-fly zone is officially in place in the eastern part of Libya, and it is expected to expand in coming days as coalition strikes take out more of Gadhafi's air defenses.