SAN ANTONIO (AP) — Democrats say a Republican plan to hold two primary elections next year amid the uncertainty of Texas redistricting would burden taxpayers and diminish voter turnout.

Election administrators from Dallas and Bexar counties testified Tuesday in federal court that holding two primaries would double taxpayer costs into the millions of dollars. That comes in response to a plan filed by the Republican Party of Texas to hold primaries in March and May.

Under the GOP plan, primaries for the president, U.S. Senate and other statewide races would be held March 6. Primaries for state legislative and congressional seats would be May 29.

The plan surfaced after the U.S. Supreme Court placed a hold on the redistricting map drafted by a federal panel, adding to the already deeply complicated legal wrangling.