President Obama's threat of military action in Libya drew liberal dissent late Friday, as lawmakers demanded that the president ask for a formal declaration of war before using military powers.

Rep. Dennis Kucinich (D-Ohio), a longtime liberal stalwart, pointed to Obama's remarks as a candidate in which the then-senator said that the president doesn't unilaterally have the power under the Constitution to launch a military attack without first getting a declaration of war from Congress.

"While the action is billed as protecting the civilians of Libya, a no-fly-zone begins with an attack on the air defenses of Libya and Qaddafi forces. It is an act of war," Kucinich said in a statement. 

Another top liberal, Rep. Jerrold Nadler (D-N.Y.), demanded Congressional involvement.

"The president has an obligation under the Constitution to seek the approval of Congress for any use of military force unless there is an imminent threat to the United States or its allies," he said.

Obama threatened military action against Libya, in cooperation with U.S. allies, unless its leader, Moammar Gadhafi, immediately ceases using military power against citizens protesting his regime. The president didn't specify what military option would be used if Gadhafi didn't comply, though Obama did rule out the use of ground troops.

Whatever the case, Kucinich demanded that Obama come to Congress first, going so far as to urge Obama to call Congress back into session from the recess set for this coming week.

“I have sent a letter to Congressional leadership indicating that the national interest requires that Congress be called back quickly to Washington to exercise its Constitutional authority to determine whether our armed forces should participate in the UN mission. Both houses of Congress must weigh in," he said. "This is not for the President alone, or for a few high ranking Members of Congress to decide."

Kucinich isn't the only lawmaker to suggest that a military offensive against Libya would require a declaration of war. Sen. Richard Lugar (R-Ind.), the ranking member of the Senate Foreign Relations Committee, who was among the congressional leaders briefed Friday at the White House, has also suggested a declaration of war is needed.