The towering rotunda of the Texas State Capitol echoed with the sound of protests on Friday during the first and only public hearing on a proposed congressional map pushed by President Trump and drawn to flip five Democratic U.S. House seats in favor of Republicans.

Hundreds of people gathered to oppose the map in a tense, daylong hearing that included forceful and frustrated testimony from several Democratic members of the U.S. House whose districts were being moved, eliminated or dramatically redrawn in a map that was unveiled on Wednesday.

“It is not only racial, it is racist,” said U.S. Representative Al Green, a Democrat and vocal critic of Mr. Trump. His Houston district was shifted from south of downtown to a Republican area east of the city. “We are losing representation, and I’m going to stand against it.”

The hearing before a Texas House committee was part of a fast-track legislative process for the new map. The Texas gerrymandering effort is the first in what could become a cascading series of warring redistricting efforts between Democratic and Republican states, initiated by the president’s push to secure as many seats as possible ahead of midterm elections that almost always favor the party out of power in the White House.

The newly drawn lines were expected to pass the committee, possibly late Friday, and could come up for a full vote in the Republican-dominated body as soon as Tuesday.

“This is going to create a ripple effect around the country,” said State Representative Jon Rosenthal, a Houston Democrat and the vice chairman of the committee.