In Play’s Jackie Kucinich talks to The Post’s congressional correspondent Ed O’Keefe about the week ahead on the Hill as Congress prepares to debate the president’s proposed military action in Syria. (The Washington Post)

Leading lawmakers dealt bipartisan rejection Sunday to President Obama’s request to strike Syrian military targets, saying the best hope for congressional approval would be to narrow the scope of the resolution.

From the Democratic dean of the Senate to tea party Republicans in their second terms, lawmakers said the White House’s initial request to use force against Syria will be rewritten in the coming days to try to shore up support in a skeptical Congress. But some veteran lawmakers expressed doubt that even the new use-of-force resolution would win approval, particularly in the House.

“I think it’s going to be a very tough sell,” said Rep. Tom Cole (Okla.), who is often a key crossover Republican in compromises with the White House. For now, Cole said he is “leaning no” on approving any use of force against Syria.

His remarks came after a more than 21 / 2-hour classified briefing that drew 83 lawmakers to the Capitol, GOP aides said. They flew in from across the country on 24 hours’ notice for a rare Labor Day weekend meeting. The briefing, run by five senior national security officials, began the administration’s all-out effort to win support for what Obama has said would be a limited strike against military targets to punish Syrian President Bashar Al-Assad’s regime for carrying out a chemical attack.

White House officials have less than two weeks to secure backing in the House and the Senate, which will not formally return from their regular end-of-summer break until Sept. 9. They are expected to then immediately begin debate on military authorization, with votes by mid-September.

Congressman Scott Rigell (R-Va.) spoke with In Play's Chris Cillizza about the letter Rigell wrote to the president demanding a Congressional vote on Syria and the moral questions surrounding the current conflict there. (The Washington Post)

Secretary of State John F. Kerry, who has been talking to his former colleagues in the Senate, predicted victory during appearances on five Sunday talk shows.

Lawmakers from both parties said Sunday that the administration has presented convincing evidence that Assad’s government carried out the attack, citing Sunday’s closed-door briefing in an auditorium in the Capitol Visitor Center and other classified presentations that they received in the past week. The key stumbling block, they said, was the concern that a limited strike would not be an effective deterrent and would only draw the U.S. military deeper into Syria’s civil war.

“I don’t think there’s a lot of doubt that the regime undertook this attack. There’s a great deal of skepticism that a limited strike is likely to be effective,” said Rep. Jim Himes (D-Conn.), a member of the House Intelligence Committee.

The uncertain outcome is rooted in a Congress that has proved deeply factionalized and dysfunctional. With Democrats running the Senate and Republicans the House, the two sides have fought to a near legislative standstill on nearly every major issue. A proposal to stiffen background checks for gun buyers died in the Senate this spring, despite having the support of 90 percent of the public. A comprehensive overhaul of immigration laws, also backed by a majority of voters, has stalled.

Add to that mix a heated debate on something as consequential as war and its constitutional underpinnings, and the atmosphere on Capitol Hill could grow even more toxic.

The most difficult hurdle comes in the House, which has been incapable this year of approving what in the past were considered perfunctory measures. The farm bill, usually a bipartisan celebration of agriculture policy, failed in late June.

Compounding the troubles is that the debate on Syria comes just as Congress is poised to renew the fiscal showdown with Obama on federal spending and raising the debt limit so the Treasury does not default.

The Syria deliberations will not fall along the normal ideological fault lines. Obama cannot count on the near-universal support he usually has among the 201 House Democrats, a caucus in which doubts are plentiful.

Aware of the growing bloc of Republican isolationists, senior GOP aides warned Sunday that a large number of Democrats will have to support the use-of-force resolution for it to have any chance. Advisers in both parties described the measure as a “vote of conscience” that House Speaker John A. Boehner (R-Ohio) and Minority Leader Nancy Pelosi (D-Calif.) will not be lobbying lawmakers to support.

Obama’s allies said the first order of business will be to work with the administration to redraft the resolution, which was sent to Capitol Hill on Saturday night and barely filled one page. It had no prescriptions for what type of military action could be carried out or its duration.

Sen. Patrick J. Leahy (D-Vt.), the dean of the Senate and chairman of the Judiciary Committee, told reporters that the resolution is “too open-ended” as written. “I know it will be amended in the Senate,” he said.

Sen. Pat Roberts (R-Kan.), a former chairman of the Intelligence Committee, said, “That has to be rectified, and they simply said in answer to that they would work with the Congress and try to come back with a more prescribed resolution.”

Rep. Chris Van Hollen (D-Md.), a former Senate staffer who inspected chemical weapons attacks by Saddam Hussein’s government against its own citizens in Iraq in the 1980s, said he will push to add language that would limit the length of the mission and prohibit putting U.S. troops on the ground in Syria.

Such provisions could gain support from lawmakers who want to rein in the Obama administration, without hampering the goals of the mission — which the president has said should be limited to missile strikes against military targets.

Two key Obama allies, Sens. John McCain (R-Ariz.) and Lindsey O. Graham (R-S.C.), are slated to meet with White House officials Monday, following their criticism this weekend that the president should be calling for a more expansive attack on Assad’s forces to help push him out of power.

McCain was also critical of the decision to seek congressional approval, pointing to Obama’s declaration months ago that a chemical attack would be a “red line” that, if crossed, would be met with military force.

“He didn’t say that ‘it’s a red line, and by the way, I’m going to have to seek the approval of Congress,’ ” McCain said on CBS’s “Face the Nation.”

The two Republicans’ support would be crucial to securing Senate passage, though the outcome in the House would remain in doubt.

“The evidence at this point is overwhelming,” said Rep. Sander M. Levin (D-Mich.), adding that “we must respond” to such a drastic use of chemical weapons.

Rep. Scott Rigell (R-Va.), who led the effort to force a congressional vote on an attack, said “80 percent” of the skeptics in the room doubted that a limited strike would achieve a clear result and feared that it might instead lead to bad consequences. “There is more a question of: Is this the right approach?”

Lawmakers said they expect to hear more from the Obama administration in the coming days.

“There’s more reading to do, and that will happen over the course of the week,” said Rep. Mike Quigley (D-Ill.), who said he was undecided about how he would vote.

So is Rep. Scott DesJarlais (R-Tenn.), who said: “I’m just not sure the case has been clearly made.”