(Adds Trump, Cornyn, Cruz, White House comments; other details)
WASHINGTON/AUSTIN, Texas, Aug 29 (Reuters) - The U.S. Congress started to come to grips on Tuesday with crafting a multibillion-dollar Hurricane Harvey emergency aid package that President Donald Trump suggested could be historically large, without providing specifics.
On a tour of rescue operations after catastrophic flooding in Texas and Louisiana, with rain still pounding Houston and New Orleans, Trump told officials and reporters at a briefing that he was working with Congress on an aid package.
"It's going to be a costly proposition," he said. "I think we'll come through ... with the right solution."
He added, "But probably there's never been anything so expensive in our country's history and never been anything so historic in terms of damage."
Lawmakers said it was too early to estimate the price-tag for U.S. taxpayer assistance on Harvey, which has killed at least 11 people and paralyzed Houston.
Hurricane Katrina, which killed at least 1,200 people in 2005, was the most damaging storm in U.S. history. After Katrina, and two smaller hurricanes that followed behind it, the U.S. government devoted $100 billion to relief and recovery, said the Congressional Budget Office.
John Cornyn, the Senate's No. 2 Republican, said Harvey recovery aid will take time. "There may be several different appropriations bills," Cornyn told KTRH Radio in Houston.
"What I would personally like to see is some emergency upfront funds to help with the temporary expenses, but as you can imagine, it is going to take a while to assess the losses."
The head of the U.S. House of Representatives' Appropriations Committee said the panel was prepared to provide the funding needed.
Republican Representative Rodney Frelinghuysen said in a statement: "We are awaiting requests from federal agencies who are on the ground, and will not hesitate to take quick action once an official request is sent."
Senator Ted Cruz said on the Hugh Hewitt radio show, "By any measure it is going to be billions upon billions of dollars."
Two senior White House officials said hurricane relief might be handled in Congress as a special emergency request, not attached to other spending legislation. Congressional leaders have not said exactly how they will handle the aid package.
House conservatives may favor a standalone measure. "My sense is that they'd want a relief aid package to be a standalone that doesn't have a lot of unrelated stuff added on," said Alyssa Farah, spokeswoman for the conservative House Freedom Caucus. (Additional reporting by Patricia Zengerle; Editing by Kevin Drawbaugh and James Dalgleish)