Sens. John McCain (R-Ariz.), left, and Lindsey Graham (R-S.C.) speak with… (Evan Vucci / Associated…)
WASHINGTON — The White House appealed Monday to two of Congress' most powerful interests — protecting Israel and challenging Iran — as President Obama and his aides scrambled to win lawmakers' support for a resolution authorizing punitive missile strikes in Syria.
Obama led the full-throttle Labor Day lobbying campaign by dialing up congressional leaders and huddling for an hour with two Republican hawks, Sens. John McCain of Arizona and Lindsey Graham of South Carolina, who now may prove pivotal to the president's aims. McCain later gave a qualified endorsement, which cheered the White House.
The president is staking his credibility, and arguably his legacy, on the battle that will play out in Congress over the next two weeks. Before he leaves Tuesday night on a four-day trip to Sweden and Russia for an economic summit, he will meet with the leaders and ranking members of the key national security panels, including the Senate and House committees on armed services, foreign relations, and intelligence.
Obama is betting that a deeply divided Congress will come together on an issue that he has called a core security interest, and give him political cover to attack Syria without a United Nations mandate. The White House stands to lose a great deal if Congress refuses.
Analysts say a congressional rebuke could undermine the use of executive power and prerogatives in the future, severely damage U.S. standing with Israel and other Middle East allies, and embolden Iran, North Korea and other adversaries.
Obama worked hard Monday to avoid that scenario. McCain, who long has pushed for greater U.S. intervention in Syria, said after meeting with Obama that he would back a resolution if it included greater support for the opposition militias that have fought to topple Syrian President Bashar Assad since March 2011.
Rejecting a resolution against Syria would be "catastrophic," McCain told reporters. "It would undermine the credibility of the United States of America and the president of the United States. None of us wants that."
But in a sign of the uphill contest, Secretary of State John F. Kerry, Secretary of Defense Chuck Hagel and other senior administration officials struggled to convince skeptical House Democrats that military action was needed to punish Assad's government for allegedly using sarin nerve gas on civilians Aug. 21.
In a sometimes heated conference call, House Democrats, many of whom are still in their home districts during the summer recess, said they were getting an earful from constituents deeply opposed to launching another war, according to a Democratic aide briefed on the call.
A senior administration official said the White House was working with lawmakers to adjust the language in the resolution to address their concerns.
Obama "made clear that he was not contemplating U.S. boots on the ground or an open-ended intervention, and that he intends to undertake tailored military operations, limited in scope and duration," the official said. "We are open to working with Congress" to win authorization for use of military force.
The White House strategy for threading the needle between opposing views rests heavily on the argument that airstrikes are necessary to send a clear message about U.S. resolve. The target, the White House argues, is not just Syria.
The broader strategic goal is to prevent Iran from obtaining a nuclear weapon and to safeguard Israel's security, sensitive issues that tend to galvanize an otherwise-gridlocked Congress.
Obama has pledged to prevent Iran from building a nuclear bomb, and lawmakers are generally united on that issue. They also understand that Israel, though officially silent on how Congress should vote, is looking to Washington to help shield it from the Syrian civil war's spillover into neighboring countries.
Administration officials warn privately that a "no" vote in Congress would encourage Iran to push ahead with its nuclear development program and would make it harder for the United States to intervene if Tehran decides to build a bomb.
Some officials say pro-Israel advocates who have leverage among House Republicans may play a key role in the coming debate.
Conservative Christians, who are passionate defenders of Israel, can be expected to weigh in with House Republicans from the South and West, said a House Republican aide. "They're tuned in to all of this," said the aide, who was not authorized to speak publicly under office rules.
Congressional antagonism toward Iran has grown over the last decade, as lopsided bipartisan majorities repeatedly have voted for tougher Iran sanctions, sometimes against the wishes of the White House. Lawmakers have discounted arguments that economic sanctions mostly hurt ordinary Iranians, not government rulers.