Challenger Henry Cuellar (search) took a 197-vote lead over U.S. Rep. Ciro Rodriguez (search) in a Democratic primary recount, and the incumbent planned to file a lawsuit over the discovery of uncounted ballots that suddenly turned up in one county.

Cuellar, a Laredo lawyer and businessman, had trailed Rodriguez by 126 votes on primary night in the solidly Democratic district with more than 48,000 votes cast. He asked for the recount last week.

The recount, which started Tuesday, turned up more than 300 uncounted ballots in a ballot box in Zapata County, and Democratic officials said Webb County's recount showed 115 more votes than there were ballots cast.

"It stinks to high heaven, to be honest with you," said John Puder, a top adviser to three-term incumbent Rodriguez.

Puder said Rodriguez planned to file a lawsuit challenging the Zapata results.

The Zapata County discovery represented nearly 10 percent of the total ballots cast in the sparsely populated county on the Rio Grande south of Laredo.

Doroteo Garza, overseeing the Zapata primary, disputed any suggestion that anything improper occurred, though he said he's not sure why the ballots were overlooked in the original count.

"Everything was in the box — they were sealed, locked and they've been kept in the International Bank of Commerce vault in Zapata," Garza said. "The seals were not broken."

All of the district's counties had been scheduled to complete their recalculations Thursday. However, a recount of the recount in Webb County won't be finished until Sunday, said Mike Lavigne, spokesman for the Texas Democratic Party.

The winner of the Democratic primary in District 28 will face the winner of an April 13 runoff election between Republicans Jim Hopson and Francisco Canseco. The district is strongly Democratic, and Rodriquez has won with as much as 80 percent of the vote.

The district was substantially redrawn during last year's heated redistricting battle. Republicans hope the new map will help them win at least 22 of Texas' 32 congressional seats, now split evenly between the parties. Democratic legislators twice fled the state in attempts to thwart the GOP effort.

Cuellar, a Laredo lawyer and businessman who served briefly in the cabinet of GOP Gov. Rick Perry, came close to upsetting Rep. Henry Bonilla in 2002, but the redistricting split Laredo, diluting Cuellar's base there and throwing him into the contest with Rodriguez.