The House will take up legislation to provide $6 billion in funding in response to the flooding and destruction caused by Hurricane Harvey, which Senate Majority Whip John Cornyn this week called a "down payment" on what could be the costliest federal disaster relief in history.

A top Republican aide told the Washington Examiner Congress expects the Trump administration to send the request shortly.

It will not be attached to any of the pending fiscal 2018 legislation and will instead be introduced as a standalone bill.

Cornyn, R-Texas, said this week that the catastrophe in Houston required immediate funding, rather than waiting for money to be included in spending legislation due by the end of September.

"We would like to get a down payment early, so we can meet the unmet needs early, while we compile the information we need to qualify for the various categories of federal assistance," Cornyn said. "What we are going to try to do is build that case, with a down payment up front."

Some estimates suggest damage will exceed $100 billion. Superstorm Sandy, which struck the East Coast in 2012, resulted in a federal government assistance package worth $50.5 billion.