TRIPOLI, Libya - Libyan leader Moammar Gadhafi, increasingly cornered under a stunning upturn in NATO air strikes, lashed back with renewed shelling of the western city of Misrata on Wednesday, killing 10 rebel fighters.

The alliance said it remained determined to keep pounding Gadhafi forces from the air but would play no military role in the transition to democracy in the oil-rich North African country once the erratic leader's 42-year rule was ended.

In Brussels, Belgium, NATO Secretary-General Anders Fogh Rasmussen said Gadhafi's days in power were clearly numbered, making it imperative for the international community, the United Nations in particular, to gear up to help Libyans establish a new form of government.

"For Gadhafi, it is no longer a question of if he goes but when he goes," Fogh Rasmussen said at a meeting of NATO defense ministers.

"We do not see a lead role for NATO in Libya once this crisis is over," he said. "We see the United Nations playing a lead role in the post-Gadhafi, post-conflict scenario."

The alliance said it was acting in the skies over Libya purely in accordance with the U.N. mandate to protect the Libyan people from Gadhafi. The resolution did not include any post-conflict peacekeeping.

French Defense Minister Gerard Longuet said: "NATO has a military vocation, and rebuilding Libya is a civilian issue. So really, simply, in order to rebuild Libya, if the Libyan people ask for it, because it is first of all an issue for the Libyan people, it is the job for civilian international institutions - and not military - to bring a response."

The Libyan rebels, too, have made it clear they have no appetite to see alliance ground forces in the country once the conflict is finished.

But they remain grateful for NATO intervention and applaud the stepped-up alliance bombing, a record 66 strike sorties over Tripoli and environs Tuesday.

"We've always felt that relentless, continuous strikes would hasten the departure of [Gadhafi] or at least the circle around him, said rebel spokesman Jalal el-Gallal in Benghazi.

The cracks in the alliance also showed Wednesday.

U.S. officials said Defense Secretary Robert M. Gates pointedly prodded five allied nations to share more of the burden of the NATO-led air campaign. None committed to do more.

The officials said Gates used his final NATO meeting before retirement to press Germany and Poland to join the military intervention, and Spain, Turkey, and the Netherlands to contribute to missions against ground targets.

Meanwhile, a resolution before the Senate pressures President Obama to seek congressional consent for continued U.S. military involvement and requires the administration to provide a detailed justification for the decision to go to war.

Sens. Jim Webb (D., Va.) and Bob Corker (R., Tenn.) introduced the resolution Wednesday, expressing the same frustration as House members who on Friday voted to rebuke Obama for failing to get authorization from Congress when he ordered air strikes.

Initially the White House brushed off the nonbinding House measure, saying it had provided answers at various briefings. But Wednesday, it said it would respond to detailed questions on the U.S. mission within a two-week deadline.