(CBS/AP)-- The Obama administration said Sunday they know for sure what the Syrian government used against its own people: Sarin gas.
What they don't know for sure is whether Congress will okay a response.
The president, in a surprise speech Saturday, said he would seek congressional approval before launching any military strike. That means the debate likely won't begin for eight more days when Congress reconvenes.
Unofficially, it is well underway.
Members of Congress from all around the country streamed back to the Capitol this holiday weekend for a classified briefing from the president's national security staff.
Most of them said they're still deciding how to vote after the president granted them the input they demanded.
Rep. Jim Himes, D-Conn. Rep. Jim Himes, D-Conn. / CBS News
"There's a great deal of skepticism in the room about the utility, effectiveness and support that we would have for the kind of strike that the president has proposed," said Rep. Jim Himes, D.-Conn.
Lawmakers said they trust the administration's evidence that Syria's government gassed its own people. But that may not be enough.
"I feel terrible about the chemical weapons that have been used. However, we know chemical weapons have been used in other instances and we did not take military action," said Rep. Janice Hahn, D.-Calif.
Even members who had consulted with Mr. Obama said they were surprised by his announcement Saturday that he would seek authorization from Congress before acting.
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Arizona Republican John McCain was one of them, but he would not speculate about whether it was a political decision.
"I do not know what went into his thinking, but if that decision was to be made, in my view, it should have been made a long time ago," McCain said.
On five Sunday talk shows, Secretary of State John Kerry insisted the White House was simply being inclusive, not indecisive.
"I think the president realized in consultations with the Congress that people wanted to weigh in. And he believed, after thinking about it, that the United States of America is much stronger when we act in concert," Kerry said.
Lawmakers are well aware the president could end up looking weak abroad if Congress does not back him up. But many members said the authorization he's seeking is too broad and that the request will need to be rewritten more narrowly if it's going to have a chance of passing.