President Donald Trump on Wednesday praised "the true character of the American people" amid the devastation caused by Hurricane Harvey and pledged that "we are here with you every single step of the way."

"In difficult times such as these, we see the true character of the American people — their strength, their love, and their resolve," Trump told supporters in Springfield, Missouri, where he announced his tax-reform plan.

"We see friend helping friend, neighbor helping neighbor, and stranger helping stranger.

"And together, we will endure and we will overcome."

The death toll climbed to 22 Wednesday as Hurricane Harvey weakened into a tropical depression after making landfall a second time since Friday and sending more than 32,000 people to shelters.

"However, catastrophic and life threatening flooding will continue in and around Houston, Beaumont/Port Arthur, eastward into southwest Louisiana for the rest of the week," the U.S. National Hurricane Center said late Wednesday.

The storm is the most powerful hurricane to hit Texas in more than 50 years. On Wednesday, it went on to swamp a stretch of coast from Port Arthur, Texas, to Lake Charles, Louisiana.

Harvey was forecast to drop another 3 to 6 inches of rain on Wednesday, with a storm surge of up to 4 feet along the western part of Louisiana's Gulf Coast.

The floods shut the nation's largest oil refinery in Port Arthur, in the latest hit to U.S. energy infrastructure that has sent gasoline prices climbing.

Trump visited Corpus Christi and Austin on Tuesday for briefings on Harvey's devastation. He plans a return visit to other affected parts of Texas on Saturday.

The president said "all of America" was grieving with those who lost loved ones because of Harvey and that "our hearts are joined with yours forever."

He praised Gov. Greg Abbott, along with other federal, state and local officials — as well as first responders and law enforcement personnel — for their efforts.

"Our first responders have been doing absolutely heroic work to shepherd people out of harm's way," Trump said. "Their courage and devotion have saved countless lives.

"They represent truly the very best of America.

"We must be vigilant. We must protect the lives of our people.

"To the people of Houston and across Texas and Louisiana, we are here with you today," Trump said. "We are with you tomorrow — and we will be with you every single day after to restore, recover, and rebuild.

"Our thoughts and prayers remain firmly with the citizens and our fellow people . . . great, great people, all affected by this tragedy."

Trump later posted these tweets:

First responders have been doing heroic work. Their courage & devotion has saved countless lives – they represent the very best of America! pic.twitter.com/I0gvCQLTKO — Donald J. Trump (@realDonaldTrump) August 31, 2017

Texas & Louisiana: We are w/ you today, we are w/ you tomorrow, & we will be w/ you EVERY SINGLE DAY AFTER, to restore, recover, & REBUILD! pic.twitter.com/YQb82K2VSB — Donald J. Trump (@realDonaldTrump) August 30, 2017

The Associated Press contributed to this report.