After seeing just a sample of the damage in Texas from Hurricane Harvey, President Donald Trump on Tuesday declared that the storm may present the United States with the largest recovery cost ever from a tropical weather system, as flood waters continued to rise in the Houston metropolitan area, and more evidence arrived of severe storm damage up and down the Texas Gulf Coast.

"Probably there has never been anything so expensive in our country's history," Mr. Trump said in a briefing with Texas officials and members of Congress in the state capital of Austin. "There's never been anything so historic in terms of damage."

In each of his stops in the Lone Star State, Mr. Trump vowed to make sure the feds would stand by Texas, to help people rebuild after the storm.

"We're going to be working with Congress in helping out the state of Texas," the President said.

"It's going to be a costly proposition," he added.

Earlier in the day at a firehouse near Corpus Christi, the President made the same public vow of support for Texas.

The President's visit to Texas came 12 years to the day that Hurricane Katrina slammed into Louisiana, ultimately causing a major failure of the levee system in New Orleans, which forced an emergency effort to pluck people from rooftops and floodwaters across that region - it was a scene being repeated in and around Houston again on Tuesday.

The focus on water rescues in Houston was still overshadowing the damage reports from elsewhere up and down the Gulf Coast, where severe damage occurred on Saturday when Hurricane Harvey came ashore.

"We want to do it better than ever before," Mr. Trump said of the recovery efforts at a briefing with top federal and state officials. "We want to be looked at in five years, and ten years from now as, this is the way to do it."

"This was of epic proportion; nobody has ever seen anything like this," the President added.