A growing number of House lawmakers are pushing President Barack Obama to bring Congress back into session before he orders a U.S. military strike in Syria.

Nearly three dozen lawmakers signed a letter spearheaded by Virginia Republican Scott Rigell, which urges the president “to consult and receive authorization from Congress before ordering the use of U.S. military force in Syria.”

“Engaging our military in Syria when no direct threat to the United States exists and without prior congressional authorization would violate the separation of powers that is clearly delineated in the Constitution,” reads the letter, slated to be sent to Obama on Wednesday.

The missive also takes issue with the military’s 2011 operations in Libya. The administration said an authorization from Congress was not required in Libya because activities were limited, were conducted under the umbrella of NATO and did not constitute “hostilities” as described in the War Powers Resolution.

“If the use of 221 Tomahawk cruise missiles, 704 Joint Direct Attack Munitions, and 42 Predator Hellfire missiles expended in Libya does not constitute ‘hostilities,’ what does?” the letter asks.

“If you deem that military action in Syria is necessary, Congress can reconvene at your request,” the letter says. “We stand ready to come back into session, consider the facts before us, and share the burden of decisions made regarding U.S. involvement in the quickly escalating Syrian conflict.”

According to Rigell’s office, the list of signatories continues to grow, but as of Tuesday evening, the letter included Democrats Zoe Lofgren of California, Rush D. Holt of New Jersey, Texans Beto O’Rourke and Gene Green and Oregonians Peter A. DeFazio and Kurt Schrader, along with Republicans Tom Cole of Oklahoma, Justin Amash of Michigan, Raúl R. Labrador of Idaho, Matt Salmon of Arizona, Mo Brooks of Alabama, Scott Garrett of New Jersey, Tom McClintock of California, Tom Marino of Pennsylvania, Dan Benishek of Michigan, Tom Rooney of Florida, Steve Pearce of New Mexico, Tim Griffin of Arkansas, Joe Pitts of Pennsylvania, Trent Franks of Arizona, John Campbell of California, Paul Gosar of Arizona, Lynn Westmoreland of Georgia, Joe Wilson of South Carolina, Charles Boustany Jr. of Louisiana, and Louie Gohmert of Texas.

While O’Rourke, a freshman, is so far the only Democrat to have signed onto Rigell’s call-back Congress crusade, Rep. Barbara Lee, D-Calif., on Tuesday also said she wanted a “full debate” in advance of military intervention in Syria.

“While the use of chemical weapons is deeply troubling and unacceptable, I believe there is no military solution to the complex Syrian crisis,” Lee said in a statement on her Facebook page. “Congress needs to have a full debate before the United States commits to any military force in Syria — or elsewhere.”

Lee was famously the only House member to vote against authorizing military force in the response to the Sept. 11, 2001, terrorist attacks.

Rep. Jim McGovern, D-Mass., who voted against the initial authorization of force in Iraq in 2002 and has been one of Congress’ most vocal opponents of the wars there and in Afghanistan, put out a statement Monday that condemned the violence in Syria while expressing reluctance to put troops on the ground of yet another country.

“I am deeply troubled by reports that the Assad regime may have used chemical weapons against their own people. If those reports are confirmed, the international community must be united in its response to these grave human rights violations. That response must pay special attention to avoiding additional civilian casualties to an already-suffering civilian population,”  McGovern said.

“We must also remain very cautious about military intervention in light of the terrible price our soldiers and their families have already paid in Iraq and Afghanistan,” he added.

The White House has been careful to note that the options they are considering do not include putting soldiers on the ground in Syria.