A two-term Republican House member has penned a letter to President Obama in which he criticizes the administration’s military action in Libya as “unlawful and unconstitutional.”

And Rep. Dennis Kucinich (D-Ohio) wrote to Obama on Thursday, informing the president that he intends to introduce an amendment next week that would defund the U.S. military intervention in Libya.

California Republican Rep. Tom McClintock sent his letter Wednesday in response to a letter Obama sent Monday to House Speaker John Boehner (R-Ohio) and Senate President Pro Tem Daniel Inouye (D-Hawaii) defending his authority to launch U.S. military operations.

“The War Powers Resolution unambiguously defines three circumstances under which the President as Commander in Chief may order United States Armed Forces into hostile action: ‘(1) a declaration of war, (2) specific statutory authorization, or (3) a national emergency created by attack upon the United States, its territories or possessions, or its armed forces,’” McClintock wrote. “Your letter cites none of these conditions.”

“With all due respect, I can only conclude that your order to United States Armed Forces to attack the nation of Libya on March 19, 2011 is in direct violation of the War Powers Resolution and constitutes a usurpation of Constitutional powers clearly and solely vested in the United States Congress and is accordingly unlawful and unconstitutional,” the letter concluded.

McClintock’s letter follows one penned to Obama by Boehner on Wednesday in which the speaker called on the president to answer a series of questions about U.S. involvement in the Libyan conflict, including a “fundamental question”: “What is your benchmark for success in Libya?”

Kucinich, who is co-sponsoring his amendment with Reps. Walter Jones (R-N.C.), Pete Stark (D-Calif.) and Ron Paul (R-Texas), wrote to Obama that he believes the administration’s “missteps so far seriously compromise the course of military intervention you have initiated.”

“The only way I can see to correct them is to stop U.S. participation in the war entirely,” Kucinich wrote. “As such, I intend to offer an amendment to the next general funding measure to be considered by Congress to defund U.S. military intervention in Libya. Congress must have the latitude to make an informed decision under circumstances in which Congress’s predictable desire to support the troops does not skew the debate on the war’s legitimacy.”

The White House has defended U.S. involvement in Libya, saying that its action is within the president’s authority and that a formal declaration of war was not necessary. Obama aides have also emphasized that they “welcome congressional support” and dialogue on the matter.

Still, with Obama facing criticism from lawmakers of both parties – including Sen. Dick Lugar (R-Ind.), a respected voice on foreign policy and a longtime ally of Obama’s on foreign policy issues – a showdown appears imminent next week when Congress returns from a weeklong recess.

A Gallup poll released Tuesday showed that 47 percent of Americans approve of U.S. and allied military action in Libya while 37 percent disapprove. That the number approving is greater than the number disapproving is a positive sign for the White House – but as Gallup notes, the 47 percent approval rating is lower than that found in its polling in the wake of other conflicts since the mid-1980s.