Credit: Manuel Balce Ceneta/AP Photo

While President Obama considers options for responding to a purported chemical weapons attack in Syria, several senior administration officials are conducting a full-court press to drum up support for a military response. They are consulting with key members of Congress to keep them apprised on strings of intelligence as they are being developed and the possibilities that await the president's approval.

Beyond the outreach from senior administration officials, ABC News has learned that in recent days Sen. John McCain, R-Ariz., has personally spoken with President Obama, his 2008 presidential campaign rival, to discuss America's response, according to an aide to McCain.

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McCain, who also connected with National Security Advisor Susan Rice, questioned whether an air strike would be effective and offered suggestions for additional actions the administration could take against the Syrian government.

"Will those attacks just be a retaliation and [Syrian President Bashar al-Assad] basically goes on as normal?" McCain asked during an appearance on Fox News today. "Or will those attacks degrade his capabilities, particularly his air capabilities, which you could do easily with standoff weaponry and start getting weapons that people need, Gen. Idris and his people need, in order to reverse the momentum on the battlefield.

"If it's not that, then it's simply, frankly, it will lead to a reduction in the United States' credibility in the region," he added. "But if we do it right and reverse the momentum here, I think that it could really have an effect in the eventual overthrow of a person who is clearly now a war criminal by using these weapons of mass destruction."

Secretary of State John Kerry has also placed a number of calls to top members of committees with jurisdiction in the matter, including House Foreign Affairs Chairman Ed Royce, R-Calif., and Ranking Democrat Eliot Engel, D-N.Y.

"I am pleased that the administration is consulting with Congress on this important foreign policy issue," Engel said after a call. "In our conversation, I expressed my view that we should respond to the Assad regime's use of chemical weapons in an appropriate manner, that we should do so quickly and in concert with our allies."

A spokesman for Royce said that the chairman "discussed the situation in Syria" with Kerry late Monday, but did not divulge details of the conversation.

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Kerry also connected with Senate Foreign Relations Chairman Bob Menendez, D-N.J., as did U.S. Ambassador to the United Nations Samantha Power, while the ranking Republican on the committee, Sen. Bob Corker, R-Tenn., spoke to "administration officials" numerous times throughout the past several days, according to an aide.

Sen. Carl Levin, D-Mich., the chairman of the Senate Armed Services Committee, said he was briefed today by the administration.

"The administration is proceeding cautiously, consulting with our allies and other countries in the region to respond to the Assad regime's use of chemical weapons against the Syrian people," Levin said. "The president is considering a broad range of options that have been presented by our military leaders."

Moreover, "senior" Defense Department officials have reached out to House Armed Services Chairman Buck McKeon, R-Calif., and ranking Democrat Adam Smith of Washington state to discuss the crisis, according to committee aides.

"The president established a red-line policy," McKeon said Monday evening after his conversation with administration officials. "Drawing red lines before you know what you are willing to do to back them up is folly, but now that American credibility is on the line, the president cannot fail to act decisively."

While the State Department said that Congress will receive a classified briefing of the intelligence and evidence of the Syrian regime's use of chemical weapons, a spokesman to House Speaker John Boehner, R-Ohio, said there are no current plans for a classified briefing. So far, the consultations have been limited to senior congressional leadership and the top-ranking members of relevant committees in the House and Senate.

A congressional source said House Minority Leader Nancy Pelosi, D-Calif., "was personally briefed by National Security Advisor Susan Rice late yesterday [Monday]." Tony Blinken, the Deputy National Security Advisor, also briefed House Democratic Whip Steny Hoyer, the No. 2 Democrat in the lower chamber, as well as House Majority Leader Eric Cantor, R-Va.

Rep. Duncan Hunter, R-Calif., a member of the House Armed Services Committee and veteran of the wars in Iraq and Afghanistan, visited the Syrian-Jordanian border today with a congressional delegation and said the extent of U.S. involvement in potentially removing Assad from office should be limited to training and arming of the opposition.

"In the event Assad is removed, it's important that American alliances are capable of influencing events in Syria," Hunter said. "If America is to have any immediate role in the removal of Assad, training and arming the opposition should be the extent of U.S. involvement, which is sufficient to show America's solidarity with friends in the region."

Smith was also on the bipartisan delegation that visited the Syrian border.

Others, like Rep. Barbara Lee, D-Calif., are pleading with the president to refrain from any military intervention, whatsoever.

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

Some members also seem weary of any military intervention in Syria given the uncertainty of the intelligence coupled with the unpleasant lesson many experienced with Iraq and weapons of mass destruction.

"The United States must remain cautious and pragmatic in our response," Colleen Hanabusa, D-Hawaii, warned in a statement. "The last decade of conflict in Iraq and Afghanistan demonstrated what comes of war waged with poor planning. We cannot haphazardly enter another conflict with a sovereign nation. Questions still remain about the identity and intentions of the Syrian opposition to the Assad regime, and I believe we need clear answers before moving forward."

On Monday, Boehner had what his office termed as "preliminary communication" with the White House, although an aide said Boehner, who was on the call, did not personally speak with Obama.

"The speaker made clear that before any action is taken there must be meaningful consultation with members of Congress, as well as clearly defined objectives and a broader strategy to achieve stability," Michael Steel, a spokesman for the speaker, wrote in a statement Monday.

Some members of Congress, such as Rep. Justin Amash, are demanding that the president first acquire congressional authorization before going forward with any sort of military strike.

Amash, a second-term Republican from Michigan, asked Boehner today to call the House of Representatives back into session for a debate and vote on authorization, and asserted that a strike authorized by the president without congressional authorization is "unquestionably unconstitutional" and "illegal," citing the War Powers Act.

Rep. Thomas Massie, R-Ky., agreed - pointing to Article 1, Section 8 of the Constitution, which gives Congress - not the President - the power to declare war.

Despite U.S. military action in more than a dozen theaters of conflict over the past 70 years, the United States has not formally declared war on any country since World War II, when it declared war on Bulgaria, Hungary and Romania on June 5, 1942.

Congress last authorized U.S. military combat for Operation Iraqi Freedom in 2003, although the president has authorized military action against countries such as Libya as recently as 2011.