Senate Democratic Leader Chuck Schumer said Wednesday that Democrats are prepared to fight with Republicans over tax reform, just hours before Trump traveled to Missouri to build momentum for a Republican legislative effort.

"This is going to be one of the biggest fights of the next three, four months, and Democrats are ready for it," the New York senator told reporters on a call hosted by a left-leaning group organized to oppose tax cuts for high earners.

Under Schumer, all but three Senate Democrats have said they won't support tax legislation that cuts taxes for high-income people or adds to federal deficits.

Trump is set to cast the tax effort in populist terms Wednesday, and will describe it as a benefit to middle-class workers to create a more favorable tax system for U.S. businesses relative to their global peers.

Schumer, though, said Wednesday that he didn't expect a Republican-only tax plan that cuts top rates for individuals to appeal to the middle class.

If the yet-to-be-unveiled legislation eventually does lower taxes for the wealthy, "the American people are going to rise up against it," Schumer warned. The call was hosted by the "Not One Penny" campaign, which has launched advertisements opposing the GOP tax effort.

Trump was set to deliver his address early Wednesday afternoon in Springfield, Mo.