It’s going to take time before Moammar Gaddafi and his family are gone from power in Libya, and, frankly, the ending may not come until the dictator is assassinated by a member of his family or a Libyan military or security officer.

Defense Secretary Robert M. Gates delivered those messages to Congress last week as he repeatedly preached patience before the House and Senate armed services committees.

In contrast, Sen. John McCain (R-Ariz.) has remained the commander of the impatient crowd, those who want to plunge ahead militarily, ignoring lessons from Iraq and Afghanistan.

There also is a congressional Greek chorus, those Republican and Democratic politicians who now question President Obama’s decision to intervene and even his authority to act. They have forgotten that in late February and early March a rush of lawmakers called for a no-fly zone and protection for protesting Libyans.

A bit of background:

l In late February, McCain, along with Sen. Joseph I. Lieberman (I-Conn.), called for a no-fly zone, arms and humanitarian assistance, as well as recognition of a nascent Libyan opposition group.

l On March 1, the Senate unanimously passed a nonbinding resolution calling on the U.N. Security Council “to take such further action as may be necessary to protect civilians in Libya . . . including the possible imposition of a no-fly zone.”

l On March 2, Gates, after noting that there was a lot of “loose talk about some of these military options,’’ said that “a no-fly zone begins with an attack on Libya to destroy the air defenses.”

l On March 4, Gaddafi troops regrouped and attacked protesters, and commentators joined legislators in calls for the president to stop dithering and act. Meanwhile, the French and British governments worked for a Security Council resolution.

l On March 7, the six Persian Gulf states backed a no-fly zone.

l On March 12, the Arab League joined the call for the United Nations to create the zone.

l On March 17, Gaddafi declared that the “moment of truth” had come for Benghazi as his planes dropped bombs on the opposition-controlled city and his tanks and troops moved forward. The Security Council approved the resolution to create a no-fly zone. That night in Washington, Obama met with Gates and his national security team and decided the United States would take the lead in the no-fly program. Plans had already been drawn up in the Pentagon and at NATO for a highly complex operation that would entail dozens of warships, hundreds of aircraft, bases in several countries, and a sophisticated command-and-control operation.

l On March 18, the president discussed his decision with the congressional leadership.

l On March 19, the no-fly zone was initiated along with strikes on Gaddaf’s military units on the ground.

Today, nearly three weeks into the operation, Gaddafi remains in power in Tripoli, rebels are in control in Benghazi, ground fighting continues and NATO directs the air war.

Gates told the committees, “The removal of Colonel Gaddafi will likely be achieved over time through political and economic measures and by his own people.” The NATO-led operation will aid his departure by degrading his military capability to hold on to power through force, Gates added.

Saying the impromptu early uprisings in Libyan cities showed that citizens were “ready to rise up against this guy,” Gates said “significantly” reducing Gaddafi’s military capabilities “gives them the opportunity to do that.”

The impatient McCain and Lieberman wanted more.

Gates was repeatedly asked when and how Gaddafi would leave. By late afternoon, Gates had sharpened his answer about Gaddafi’s possible fate: “A member of his own family kills him or one of his inner circle kills him, or the military fractures, or the opposition with the degradation of Gaddafi’s military rises up again and is successful.”

McCain had earlier lectured Gates that the “purpose of using military force is to achieve policy goals’’ — including “Gaddafi leaving power.” Gates said he saw a difference between the political objective of Gaddafi’s departure and the military mission. The latter was already successful, he said, then added that he “personally . . . felt strongly” that his mission did not include regime change. “We’ve tried regime change before, and sometimes it’s worked and sometimes it’s taken 10 years.”

Members also asked about U.S. troops having “boots on the ground” in Libya. The president had said there would be no U.S. ground troops, and Gates emphasized his own view: “Not as long as I’m in this job.”

As for the opposition’s need for training and command and control, Gates said this was discussed and that other countries had the capability to meet those needs.

And finally, regarding whether Obama abided by the War Powers Act, Gates noted there had been disagreement between the Congress and every president on what the act requires, and Obama had complied when he met with congressional leadership on March 18.

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