2 September-US President Donald Trump is due to visit Texas for a second time in the wake of Hurricane Harvey.
The hurricane made landfall in the state a week ago, causing devastating floods.
Some residents have been allowed to return to their homes but flood waters are still rising in other areas.
Harvey has been blamed for at least 47 deaths, and about 43,000 people are currently housed in shelters. Mr Trump has asked Congress for $7.8bn (£6bn).
The sum would be an initial payment to help with recovery efforts following the flooding in both Texas and Louisiana, which has also hit production at America’s main petrol and oil refining centre.
Governor of Texas Greg Abbott has said the state may need more than $125bn in aid.
President Trump and his wife Melania visited Texas earlier in the week but stayed clear of the disaster zone, saying they did not want to divert resources from rescue efforts.
However, the president was criticised for not meeting victims of the flooding and for focusing largely on the logistics of the government response.
The White House said Mr and Mrs Trump would visit Houston on Saturday to meet flood survivors and volunteers, and would then travel to Lake Charles, Louisiana.
President Trump has declared Sunday a “National Day of Prayer” for victims of Hurricane Harvey.
Administration officials say there will be further requests for funds when the full impact of Hurricane Harvey becomes known.
In a letter to House of Representatives Speaker Paul Ryan, White House budget director Mick Mulvaney warned that failure to raise the US debt ceiling could hinder recovery efforts.
The debt ceiling is a cap on the total amount the US government can borrow. Only Congress can raise that limit.
“This request is a down-payment on the president’s commitment to help affected states recover from the storm, and future requests will address longer-term rebuilding needs,” Mr Mulvaney said.
He said almost half a million households had registered for support for rental assistance and for essential home repairs.
He called on Congress to act “expeditiously to ensure that the debt ceiling does not affect these critical response and recovery efforts”. A vote on the emergency request is expected next week.
It is believed that about 80% of Texans do not have flood insurance to cover the wreckage.
Harvey dumped an estimated 20 trillion gallons of rain on the Houston area. It was later downgraded to a tropical storm but continued to batter Texas and parts of neighbouring Louisiana.
Governor Abbott has warned that the recovery programme will be a “multi-year project”.
“This is going to be a massive, massive clean-up process,” he told ABC News.
As the water recedes in Houston a huge clean-up operation is under way. Firefighters have been carrying out door-to-door searches in an operation that could take up to two weeks.
Mr Abbott warned that in some parts of the state, rivers were still rising and flooding “poses an ongoing threat”.\\
Search-and-rescue teams have continued work in Beaumont, a city of about 120,000 people near the Louisiana border, where flooding has cut off the drinking water supply.
The Environmental Protection Agency has warned that floodwater can contain bacteria and other contaminants from overflowing sewers. It said the biggest threat to public health was access to safe drinking water.
Thousands of homes and businesses remain without power, and many schools are expected to remain closed on Monday.
Meanwhile the Houston Astros, the city’s Major League Baseball team, have announced they will return home for games against the New York Mets this weekend. Tributes will be paid to those who lost their lives in the flooding.
The team abandoned their home stadium this week, playing three games in Florida against the Texas Rangers.
“We hope that these games can serve as a welcome distraction for our city that is going through a very difficult time,” Astros president Reid Ryan said.
“We hope that we can put smiles on some faces.”