Lawmakers now have another complicated task awaiting them when they return to Washington and an already packed September calendar: potentially approving billions of dollars for Hurricane Harvey recovery.
Authorizing aid opens another window for Congress to potentially play politics and bicker over policy ahead of two key deadlines.
President Donald Trump, who visited Texas on Tuesday, has promised swift help for the state after Harvey, which was the most powerful hurricane to hit Texas in more than 50 years when it came ashore Friday. A number of people have died and billions of dollars in damage have been caused in southeast Texas, where some areas could see as much as 50 inches of rain from the lingering storm. Rescue operations are ongoing in Houston and surrounding areas, where flooding has stranded residents.
When Congress gets back from its August recess, it will have to respond to the storm as it already faces two politically contentious deadlines. Treasury Secretary Steven Mnuchin has warned that the U.S government will hit its borrowing limit on Sept. 29 and potentially risk defaulting on its obligations without raising the debt ceiling. Lawmakers also need to pass a funding bill before Sept. 30 to avoid a government shutdown.
The hurricane adds another wrinkle to what could already become a messy set of negotiations.
"Congress can always find time, find a way to do the things it needs to do in an emergency," said Steven Billet, director of the legislative affairs program at the George Washington University Graduate School of Political Management. "The bigger question is who may or may not be tempted to play politics with [disaster relief.] ... The temptation will most assuredly be there for a lot of people."
Both raising the debt limit and funding the government will likely come with complications. The White House has called for a "clean" debt ceiling increase without other provisions attached. Some conservative Republicans have previously called for spending cuts along with raising the borrowing limit and could seek concessions in the bill this time around.
Trump has also threatened a government shutdown if Congress does not fund his proposed wall along the U.S.-Mexico border. Democrats have opposed approving money for the project.
Throwing in Hurricane Harvey relief my make September even more complicated.
Even legislation to approve disaster aid has proven contentious in the past. In 2013, many Republican lawmakers — including some from now storm-ravaged Texas — voted against a Hurricane Sandy relief bill. Some said it contained too much funding for unrelated provisions or sought corresponding spending cuts.
Rep. Mark Walker, R-N.C., head of the influential Republican Study Committee, told CNBC he is not taking a hard line on spending reforms with disaster relief funding.
The potential effect of Harvey aid on Congress' ability to meet its goals in the coming weeks will depend on whether lawmakers attempt to approve aid on its own or tie it to a spending or debt ceiling bill, said Molly Reynolds, a fellow in governance studies at the Brookings Institution.
On its own, an aid vote could face opposition from some Republicans. But that backlash may fade with Democratic President Barack Obama out of office, Reynolds said.
She said that attaching Harvey relief funding to a short-term bill to keep the government running could help to "smooth over" disagreements among Republicans and make it easier to pass.
But either conservatives insisting on spending cuts or Trump pushing for the bill to include border wall funding could make the process more difficult, Reynolds added.
On Monday, Trump pledged that the government would take "rapid" action to fund disaster relief.
"I think that you're going to see very rapid action from Congress, certainly from the president … you're going to get your funding," he said at a joint news conference with Finnish President Sauli Niinisto.
"We think that Congress will feel very much the way I feel ... I think you'll be up and running very, very quickly," Trump added.
In a statement Monday, House Democratic Leader Nancy Pelosi said, "Republicans must be ready to join Democrats in passing a timely relief bill that makes all necessary resources available through emergency spending."
Sen. Ted Cruz, R-Texas, has been forced to defend his 2013 vote in recent days as Harvey wreaks havoc in his home state. On Monday, he told NBC News that the bill was "filled with unrelated pork" and that "two-thirds" of it had "nothing to do with Sandy."
But the vast majority of the bill did have to do with Sandy recovery, The Washington Post found.
Both Billet and Reynolds ultimately expect Congress will pass a small aid package relatively soon after it returns before debating a larger measure later in the month. It will fall on the Trump administration to estimate how much funding will be needed long term, which will take until experts can assess the damage in the coming weeks.
— CNBC's Ylan Mui contributed to this report