Independent presidential candidate Ralph Nader (searchon Monday sued Texas' top election official to try to get onto the state's ballot, claiming that a petition signature requirement is unconstitutional.

Nader's campaign also applied to the Texas Secretary of State's Office for a place on the general election ballot but said it would not submit the more than 50,000 voter signatures it had collected.

Ballot access rules required the campaign to collect at least 64,076 signatures by 6 p.m. EDT Monday from registered voters who did not vote in this year's Democratic or Republican primaries. The figure equals 1 percent of the presidential votes cast in Texas in the 2000 presidential election.

Nader campaign manager Theresa Amato said in a letter to Texas Secretary of State Geoffrey Connor (searchthat the requirement for petition signatures and a 60-day timetable for collecting them were "an unconstitutional and discriminatory burden as applied to independent candidates in the State of Texas."

Amato's letter said the provisions violate the First and Fourteenth Amendments of the U.S. Constitution.

Nader, who has yet to qualify for any state ballot, and three Texas voters who want to be his presidential electors filed the lawsuit, which seeks an injunction against the state's ballot access law, the Nader campaign said.

"They create these situations that make it impossible for independents to get on the ballot," said Nader spokesman Kevin Zeese. He said the campaign expects to use the court case to get Nader onto the ballot in Texas, President Bush's (searchhome state.

Texas has one of the earliest deadlines to qualify for the presidential ballot and requires independent candidates to gather a larger number of signatures — about 20,000 more — than third-party contenders.

In response to the lawsuit, Connor said the ballot requirements for independent candidates had been in place for 20 years. Connor also noted that Ross Perot in 1992 and 1996, and Pat Buchanan in 2000 got on the state's ballot.

Nader's campaign disputed that, saying they were Reform Party candidates, not independents. However, Connor's office said Perot and Buchanan appeared on the ballot as independents and had to adhere to the rules for independent candidates.

The campaign complained last week that its volunteers have been banned from some street festivals, libraries and public university campuses in Texas, making it difficult to gather signatures.

Nader, a longtime consumer activist, ran for president in 2000 as the Green Party candidate and won 2.7 percent of the vote nationally. Some Democrats blamed him for pulling votes away from Democrat Al Gore, causing him to lose to Republican George W. Bush.

Nader appeared on the ballot in 43 states and the District of Columbia in 2000 after filing eight lawsuits to challenge ballot access rules.