An appeals court on Monday reversed itself and ruled against Rep. Ciro Rodriguez (search) in a lawsuit alleging vote fraud during the Democratic primary in March.

The ruling ends Rodriguez's bid in state court to overturn the 58-vote lead held by his opponent, Henry Cuellar (search).

"This is the moment our campaign has been waiting for," Cuellar said in a statement. "We have won at the polls and we have won in the courtroom. Now it's on to November and victory."

Rodriguez, reached by phone in Washington, said he and his campaign team will examine other legal avenues to challenge Monday's ruling, including a possible federal court challenge.

"There's no doubt that I'm not going to let this one go," he said.

Rodriguez, a seven-year incumbent, led by 145 votes on primary election night. But Cuellar took the lead during a districtwide recount after more than 200 previously untallied ballots were discovered in Webb County, where he lives, and neighboring Zapata County.

Rodriguez sued in early April, alleging irregularities in the "casting, counting and recounting" of ballots in the two counties.

Later that month, he amended the suit by adding details of alleged irregularities involving "more than 100" voters. He claimed some of the voters didn't live in the district, while others gave false information to election officials in order to cast ballots.

Cuellar, a Laredo lawyer, challenged the amended lawsuit, saying it raised new claims after the filing deadline.

A state district judge agreed. But a three-judge panel of the 4th Court of Appeals ruled 2-1 that Rodriguez had the right to question the legality of the votes and that Cuellar had sufficient time to defend himself.

Monday's 5-2 vote by the full appeals court came along party lines, with the Republican majority saying that Rodriguez was trying to bring a completely different allegation to trial.

"Because Rodriguez's original petition did not have a single page, paragraph, sentence or word referring to anyone as having voted illegally," the decision said, "any reasonable person ... would be led to conclude that the sole basis for his election (lawsuit) was the vote count."

Barring a successful challenge by the incumbent, Cuellar is set to oppose Republican nominee Jim Hopson in the November general election in the heavily Democratic district.

No matter what, Rodriguez said he would run again in 2006.

"If I'm the congressman, I'm running for re-election," he said. "And if I'm not the congressman, I'm still running for re-election."