The largest super PAC backing House Democrats is creating a new fund with upward of $20 million to target congressional Republicans in Texas if legislators there follow through on plans to redraw district lines to eliminate Democratic seats ahead of the 2026 midterm elections.

At the direction of President Trump, Gov. Greg Abbott of Texas, a Republican, has called a special session of the State Legislature to remake the lines in the state in order to squeeze as many as five Democrats out of office in an effort to pad the current slim Republican majority in the House.

National Democrats have decried the redistricting effort — lines are typically drawn once a decade after the census — as an effort to rig a Republican majority.

“Republicans are trying to steal five seats in Texas,” said Mike Smith, the president of the House Majority PAC, which is creating the new account, called the Lone Star Fund.

The new account, he said, is partly a bid to tell congressional Republicans from Texas that their own jobs could be put in jeopardy by the remapping as Republican voters are shifted into formerly Democratic seats. But he said it was also a bid to recruit some unlikely Republican allies to oppose the new maps because they fear for their own careers.

“They should be scared and they should be vocal about being scared because they’re about to get a bunch of money dropped on their head,” Mr. Smith said.