LAREDO, Texas (AP) — A recount was underway Thursday in a Texas primary race between Democratic U.S. Representative Henry Cuellar and progressive challenger Jessica Cisneros after their close runoff in May.

Prior to the recount, Cuellar led Cisneros by 187 votes, or 0.4 percentage points, out of 45,429 ballots counted last week, according to an Associated Press tally. The AP will not declare a winner until the recount is complete.

It was unclear on Thursday when the recount would be complete.

The recount was called for by Cisneros, a 29-year-old immigration attorney who is trying to overthrow the South Texas congressman for the second time in as many years. She has fallen 4 percentage points in 2020 behind national support from progressive party leaders, including the Sens. Bernie Sanders of Vermont and Elizabeth Warren of Massachusetts.

Cuellar said his lead would hold in Texas’ 28th congressional district, which is heavily Hispanic and stretches to the southern border with Mexico. He stood up to his party for years on issues such as abortion and gun rights, but retained the support of Democratic leaders in Congress, including House Speaker Nancy Pelosi.

The winner will face Cassy Garcia, who won the Republican runoff for the seat in May.