Congressional lawmakers, after watching from afar as the Obama administration sent U.S. forces into Libya, have started to weigh in with legislation aimed at exercising some control over the direction -- or at least the funding -- of the mission.

After returning from recess, lawmakers are looking at drafting a proposal that would put Congress on record for or against U.S. military involvement. Those writing it want Congress to authorize the involvement, but they acknowledge such a debate would open the door for opponents who think President Obama overstepped his bounds and want to rein him in.

So far, those skeptics have targeted the funding for the military operation. Defense Secretary Robert Gates confirmed Thursday that the mission had run up a $550 million bill as of Monday, and would continue to cost about $40 million a month, now that NATO has taken the lead.

Rep. Dennis Kucinich, D-Ohio, delivering a lengthy speech Thursday on the House floor, said he wants to offer an amendment to ban funding for the Libya campaign outright.

Rep. Roscoe Bartlett, R-Md., just introduced a bill aimed at ensuring the Libya operation does not add to the deficit -- at a time when lawmakers are wrangling over how much to cut from the rest of the 2011 budget and try to slow the pace at which the country adds to its $14 trillion debt.

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The Bartlett proposal would require the president to provide Congress with a list of proposed cuts from the discretionary, non-military section of the budget to cover the military's expenses in Libya.

The role of Congress is still unclear. Obama administration officials claim they don't need Congress' permission to launch what they describe as kinetic military activity. But critics, who want to know how the Libya action is different from war, have demanded a vote, and supporters of the president's actions have started to work on a resolution, to be on the safe side.

Sen. John McCain, R-Ariz., said Thursday he is working with Foreign Relations Committee Chairman John Kerry, D-Mass, GOP Leader Mitch McConnell, R-Ky., and Sen. Joe Lieberman, I-Conn., to make sure any resolution they develop contains "language that can receive an overwhelming vote in the Senate. It would not be a good signal, otherwise."

The group, which is working with the administration, has "not yet decided" whether the resolution will be a symbolic measure, known as a "sense of the Senate" resolution, or something binding.

An aide to McCain said the group wants to introduce something "sooner rather than later," as there is a growing concern that some senators could introduce a resolution to force an end to the current mission in the north African nation.

One of those skeptical senators, Republican Rand Paul of Kentucky, on Wednesday introduced a nonbinding resolution that states the president "does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation."

Paul said earlier that the president's decision stood as a "very serious breach of our Constitution."

Senate Armed Services Committee Chairman Carl Levin, D-Mich., acknowledged Tuesday that launching a debate on a resolution authorizing military force after the fact could open the door for opponents to rally against the resolution. But lawmakers are acting out of concern for the provisions of the 1973 War Powers Resolution, which states Congress, even after the fact, must formally declare war or authorize the use of force within 60 days. It provides flexibility in certain circumstances.

Kerry said Thursday he's not sure if Congress needs to pass the resolution but said lawmakers are beginning to draft one.

Meanwhile, Gates made clear Thursday that the Defense Department cannot afford to pay for the operation on its own and would likely need to request a supplement budget to fund the operation.

Sen. Richard Lugar, R-Ind., ranking Republican on the Senate Foreign Relations Committee, expressed concern Thursday that the conflict could inflame the deficit.

"We find ourselves in a situation where Congress is debating cuts in domestic programs to make essential progress on the deficit, even as President Obama has initiated an expensive, open-ended military commitment in a country that his defense secretary says is not a vital interest," Lugar said in a statement.