Washington (CNN) - The odds of the Obama administration winning congressional support for military action against Syria were unclear Sunday as lawmakers got a classified briefing on the administration's case against the Syrian government.
Roughly 100 members of the House and Senate came back from recess for the briefing with top administration officials, according to those who attended the meeting. Many of those lawmakers - Republicans and Democrats alike - left the session skeptical and with major concerns about the language of the president's proposal.
President Barack Obama announced Saturday that he wants the United States to take limited action against Syria's government, which Washington says has used chemical weapons on its own civilians. But Obama said he will first seek authorization from Congress when the House and Senate officially return on September 9.
Changing a 'partial blank check'
Republican Sen. Roy Blunt of Missouri, who helped moderate the discussion Sunday, told reporters the biggest concern among members was "a very broad request for authority with a supposedly very narrow intent."
"I think that has to be narrowed down next week," he told reporters.
Obama administration officials said they were "open" on the language issue, Blunt said, and he believes they will have to be if they want the resolution passed. The senator indicated he is undecided and wants to hear more, but he's also skeptical that a limited mission is worth the risk of launching a strike.
Democratic Rep. John Carney of Delaware said administration officials explained why the draft resolution's wording was broad but said it was classified so he couldn't elaborate.
"There's a lot to think about," he said, adding that the decision is weighing heavily on many of his colleagues.
Democratic Rep. Chris Van Hollen of Maryland said he expects changes will be made to the proposal, which he called a "partial blank check" because it was "too broadly drafted."
"This is not a question of whether you trust the president. I do trust the president. This is a question now of what kind of authorization that Congress will give to the executive branch," he said.
He said he would like to see an amendment that would prohibit American troops from being on the ground in Syria and a separate change that would give American action in the country a firm expiration date. The U.S. should only be able to intervene after the initial strike if President Bashar al-Assad's regime continues to use chemical weapons, he said.
Rep. Eliot Engel of New York, a top Democrat on the House Foreign Affairs Committee, urged caution in adjusting the language.
"I think we can narrow it somewhat, but we have to be careful. You don't want to tie the president's hands. You want him to do what he needs to do," he said.
No plans for counting votes for now
But the main argument from the administration, according to a source familiar with Sunday's meeting, was "What will the world think of us if we vote this down?"
Historically, both parties have tended to treat votes like these as a matter of conscience, and the Republican majority in the House of Representatives has no plans to twist members' arms on a vote, according to a senior House GOP member who didn't want to speak on the record about internal talks.
Democratic supporters are hoping Minority Leader Nancy Pelosi decides to whip Democratic members to push for a yes vote. On a conference call with congressional leaders and Obama officials last week, Pelosi - who became speaker in 2006 in large part because of opposition to the Bush administration over the war in Iraq - argued in favor of acting in a limited capacity in Syria, according to sources on the call.
One GOP aide acknowledged that Republicans don't plan to count votes but argued "Pelosi needs to post a big number" for the resolution to pass the House.
Sources from both parties say votes in both chambers - especially in the House - could go either way.
If a vote were taken today, it likely would not pass, which is why the president is not calling Congress back early from its recess. The White House needs time to present its case and lobby lawmakers, and top administration officials are set to meet with members of Congress this week in addition to Sunday's briefing.
House Democratic Caucus Chairman Xavier Becerra told reporters Sunday on Capitol Hill that he doesn't think "matters of military action lend themselves to whipping."
"These are singular votes," the California representative said.
Becerra added he's still reviewing evidence and has not decided how he would vote but said if the mission went beyond targeted strikes, he would oppose it.
Sen. John McCain, who's meeting with Obama Monday, said he wants to know whether there's a plan to take out Assad's regime before he commits to a vote. If the vote were held today, however, he said he believes it could pass.
"I do believe that it can," the Arizona Republican told reporters on Capitol Hill before going into the classified meeting. "I think it depends to some degree whether the president of the United States not only makes the case to Congress, but I would recommend that he speak from the Oval Office and tell the American people why this mission is necessary."
Shadows of the past loom in present
Rep. Janice Hahn of California, who took a red-eye flight from Los Angeles Saturday night to arrive in time for the Sunday briefing, said "there was a lot of concern in the room" about the objectives of launching a strike.
Hahn, a Democrat, said she's "not there yet" on feeling confident about voting for military intervention, adding the room of about 100 lawmakers seemed "evenly divided."
"Members of Congress that came back here today are taking this very seriously, are very concerned and are asking a lot of hard questions, probably some questions that were not asked 10 years ago," she said.
Rep. Jim Himes, D-Connecticut, also referenced the Iraq War as a reason why many lawmakers want to be careful about their decision.
"There was a lot of memories of another time when a president came and said, or at least the president's people came and said, this was slam dunk intelligence, and of course, that was not an episode that most members would ever want to repeat," he said, adding that he believes most members "are thinking a lot more about the merits of the proposal than the political consequences for the president."
If the vote were held today, Himes said he would vote "no." The congressman wants to know if the president will be able to gather more international support and would like to see more details about U.S. involvement after the strike.
The congressman also said he watched the British Parliament vote against a Syria strike "with some trepidation."
"Obviously those of us who serve in the Congress watched what the House of Commons did with some trepidation. The UK has always been at our side when we've undertaken these things, and this time, they're not, so there's a lot of questions about that," he said.
Longtime Democratic Rep. Sander Levin said he was a "yes" and expressed confidence that a majority of Congress would agree with him and will "step up to the plate."
"I've been here over 30 years, I think now and then we can go beyond politics, and this is one time we need to do this," the Michigan Democrat said.
Asked if he's aware of how a U.S. military involvement might end in Syria, Levin said, "I don't think anybody's quite sure, but I think we know where we need to start."
- CNN's Alison Harding contributed to this report.