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President Donald Trump on Wednesday promoted the Republican tax reform effort, his top legislative priority.

In St. Louis, Mo., the president planned to describe the two tax reform bills currently moving through Congress as a "once in a lifetime opportunity to restore American prosperity."

The visit came as Republicans in the Senate worked feverishly this week to hammer out a tax reform bill that can garner support from both deficit hawks and more moderate senators. On Wednesday, a version of the bill moved one step closer to the Senate floor.

But major questions still remain about what the final version of the legislation will look like. Floor debate and amendments are expected later this week, with votes on the bill also potentially taking place within the next few days.

"This week's vote can be the beginning of the next great chapter for the American Worker," Trump is expected to say.

"Our focus is on helping the folks who work in the mail rooms and machine shops of America – the plumbers and the carpenters, the cops and the teachers, the truck drivers and the pipe fitters – all of the people who give their best each and every day to take care of their family and the country they love," Trump is slated to say, according to prepared remarks distributed to press. "It is not enough for the middle class to keep getting by – we want them to start getting ahead."