The Democratic governors of two of the largest states in the country issued their most explicit threats yet to Republicans in Texas: If they draw new Congressional maps to favor their party before the 2026 election, Democrats will look to do the same.

“This is not a bluff,” Gov. Gavin Newsom of California said on Friday afternoon, minutes after meeting with Democrats from the Texas House. “This is real, and trust me, it’s more real after listening to these leaders today, how existential this is.”

Gov. JB Pritzker of Illinois issued a similar pledge. “Everything is on the table,” he said on Friday.

The response from the two governors — both of whom are seen as potential Democratic presidential candidates in 2028 — followed meetings with more than a dozen Democrats from the Texas House, who had flown to California and Illinois on Friday as part of an effort to beat back an aggressive Republican redistricting effort.

“We want the country to understand what’s going on in Texas is a national battle,” said State Representative Richard Peña Raymond, a Democrat from Laredo who was part of the group that met with Mr. Pritzker in Chicago. Mr. Raymond said he stressed to the Illinois governor that the redistricting is “clearly aimed at affecting the entire country.”

Gov. Greg Abbott of Texas had called a special session of the Legislature to redraw the maps after private and public pressure from the White House. President Trump has pushed Texas Republicans to redraw their maps — though redistricting usually takes place only after the decennial census — to help preserve the party’s majority in the U.S. House. He has suggested an additional five seats could be created for Republicans in Texas out of the state’s 38 congressional districts. The party already holds 25 seats.