Syria will take center stage in Congress this week when lawmakers return from summer recess faced with a critical vote on whether to authorize President Obama to launch a military strike against the war-torn nation.
The debate over Syria has swiftly shifted attention away from other pressing matters, at least temporarily, including the need for a new temporary government funding bill, a looming debt ceiling fight and the debate over a comprehensive immigration reform bill.
Lawmakers are instead expected to begin debating a resolution that would give Obama limited authority to launch a strike against Syrian President Bashar Assad's regime in retaliation for its use of chemical weapons against its own people.
But the fate of the war resolution is far from clear.
Debate on Syria will begin in the Democratically controlled Senate, where a 60-vote threshold will likely be needed to pass the measure and many Democrats and Republicans remain either opposed to it or uncommitted.
Senate Majority Leader Harry Reid, D-Nev., said he believes the Senate will pass the resolution even though only a couple of dozen lawmakers in the chamber have pledged to support it.
In the Republican-led House, lawmakers have not even drafted their own resolution authorizing a strike, although the top House leaders in both parties have endorsed such a measure.
House Majority Leader Eric Cantor, R-Va., who publicly supported the resolution, told members in a memo to expect a "robust debate" and vote on a resolution some time in the next two weeks.
"Understanding that there are differing opinions on both sides of the aisle, it is up to President Obama to make the case to Congress and to the American people that this is the right course of action," Cantor said.
Obama will conduct a round of television interviews on Monday, followed by a televised address to the nation on Tuesday as part of a last-minute push to convince a war-weary nation and Congress to back the strike.
But even lawmakers who support military intervention say it will be difficult to win congressional approval.
"It's an uphill slog from here," House Intelligence Committee Chairman Mike Rogers, R-Mich., said Sunday on CBS's "Face the Nation."
Lawmakers attended hearings and classified briefings over the past week at which White House officials, including Secretary of State John Kerry, worked to convince them that they should give Obama the green light to attack Syria.
White House officials will continue to blanket the Capitol again this week in an effort to sway the vote in favor of a strike. Lawmakers will be offered another classified briefing Monday evening, and Democrats will caucus at least twice, including at least one meeting with White House Chief of Staff Denis McDonough.
Despite the hours of consultations so far, much of it behind closed doors and with classified materials intended to make the case for a strike against Assad, hundreds of House members remain uncommitted or are leaning against approve.
House Minority Leader Nancy Pelosi, D-Calif., has been sending daily "Dear Colleague" letters to the caucus to sway them. Her Friday memo to members acknowledged that many Democratic lawmakers want to see a diplomatic response, not a military strike.
"These efforts are not mutually exclusive," Pelosi wrote.
The uncertainty of what will happen in the House is likely to make things more difficult in the Senate, which is expected to vote first.
Cantor sent a memo Friday to fellow Republicans that was already looking past the Syria debate to a packed fall agenda.
Cantor noted that Congress will need to approve a short-term spending bill because the fiscal 2013 spending law expires Sept. 30 and without funding the government will shut down.
Cantor advocated in the memo approval of a spending bill that keeps automatic sequester spending cuts in place, returning federal spending levels to pre-2008 levels.
Cantor said the upcoming debate over increasing the nation's borrowing limit, which will come some time in October, will include an additional push for spending cuts.
"Over the past three decades during times of divided government, increases in the debt limit have been accompanied by major spending, fiscal, and regulatory reforms and I expect that model to play out once again," Cantor said.
At the center of the fall agenda is the GOP effort to block the implementation of Obama's new health care law, which has been partially delayed by the Obama administration due to problems with implementation.
The House voted about 40 times to stop the law only to have their efforts blocked by the Democratic Senate.
"We will continue to pursue the strategy of systematically derailing this train wreck and replacing it with a patient-centered system which removes Washington from health care decisions," Cantor said.
Cantor said the House "may begin considering" immigration reform measures as well, but not the broad comprehensive bill passed in the Senate earlier this year.
Instead, Cantor said, lawmakers may vote on more limited measures approved by the House Judiciary Committee that focus individually on improving border security and increasing visas for high-skilled workers.