SPRINGFIELD, Mo. - WASHINGTON — President Donald Trump placed the onus Wednesday on Capitol Hill to seize a “once-in-a-generation opportunity” and see through his push to overhaul the tax code, stumping in main street Missouri ahead of a critical legislative stretch.

“I’m calling on all members of Congress — Democrat, Republican and independent — to support pro-American tax reform,” he said in Springfield, the so-called birthplace of Route 66. “They have to do it. It’s time.”

Trump’s remarks were short on specifics and revisited elements of an outline his administration released in April, including reducing the number of income tax brackets, closing the carried-interest loophole and lowering the business tax rate to 15 percent.

They appeared intended to pressure lawmakers as their August recess comes to a close. The president has expressed his frustrations at Senate GOP leaders who failed earlier this summer to advance a plan to repeal and replace Obamacare.

“If we achieve sustained 3 percent growth, that means 12 million new jobs and $10 trillion of new economic activity over the next decade,” Trump said. “So this is our once-in-a-generation opportunity to deliver real tax reform for everyday hardworking Americans.”

He added: “And I don’t want to be disappointed by Congress, do you understand me? . . . I think Congress is going to make a comeback. I hope so.”

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The president said helping Americans keep more of what they earn should be a bipartisan proposition but criticized the minority party even as he asked for its cooperation.

“The Dems are looking to obstruct tax cuts and tax reform, just like they obstructed so many other things, including administration appointments and health care,” Trump said.

He tweeted Sunday that Sen. Claire McCaskill (D-Mo.) should be unseated and added Wednesday of tax legislation: “If she doesn’t do it for you, you have to vote her out of office.”

A senior White House official said ahead of Trump’s trip to Missouri that the president would explain why tax relief is necessary but not how he wanted it accomplished.

The conversations between the administration and Capitol Hill are ongoing with the goal of making tax code legislation a “unified proposal,” said the official, who spoke on the condition of anonymity.

Senate Minority Leader Chuck Schumer (D-N.Y.) said before Trump’s speech that any changes should go through the regular order so tax reform can be a truly bipartisan package.

He said the plan “should be deficit neutral . . . Republicans should not use fuzzy math or blatantly partisan estimates.”

He and House Minority Leader Nancy Pelosi of California said they feared the proposed cuts would benefit the wealthy at the expense of the working class and middle class.

Committee for a Responsible Federal Budget president Maya MacGuineas commended Trump’s focus on a fairer and simpler tax code but said, “Offsetting the cost of tax reform is the central ingredient in creating reform that grows the economy without exploding the debt.”

Trump on Wednesday also offered words of empathy to those suffering the wrath of Harvey in Texas and Louisiana.

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“To those affected by the storm, we are praying for you and we are here with you every single step of the way,” he said. “To those Americans who have lost loved ones, all of America is grieving with you and our hearts are joined with yours forever.”

CORRECTION: Pelosi’s title was incorrect in a previous version of this story.