IOWA CITY -- Just hours after celebrity Democrats visited Iowa City to warn against voting for Ralph Nader, nearly 2,000 people came out to hear the Green Party candidate urge them to vote for principles rather than parties.

"The Democratic and Republican parties are becoming increasingly insignificant in Washington, D.C.," as they are replaced by corporate lobbyists and political action committees, Nader said in a lengthy speech at the Iowa Memorial Union last night.

Nader, on the other hand, is becoming increasingly significant as the race between Democrat Al Gore and Republican George W. Bush tightens in the final days of the presidential campaign.

With polls showing the Green Party candidate gaining about 5 percent of the vote, Nader is not considered a threat to win any state. But Gore supporters fear that the consumer advocate's liberal base could take away votes from the vice president in one of the closest presidential elections in years.

"Frightened liberals are being sent around the country" to campaign against voting for him, Nader said.

"Al's afraid that Ralph Nader will take votes away from him," Sara Voigt, 20, of Clinton, said as she waited to hear Nader. She didn't plan to vote this year, but now she thinks she'll cast a ballot for Nader. She likes his position on raising the minimum wage to $10, providing full medical coverage and protecting a woman's right to an abortion.

She said she wouldn't vote for a candidate who didn't have a chance to win if he was saying the same thing as the other candidates.

"But it will make a difference down the road if Nader makes a good showing," Voigt said. "People will believe their opinions matter."

Nader and Green Party organizers hope he wins at least 5 percent of the vote to qualify for federal campaign funds in 2004.

Zef Wagner of Ames said he realizes that Nader could stand between a Gore victory and four years of Bush.

"But at this time I feel it is important to look long-term," the Drake University student said. "We need to fix the system, and a vote for Nader will build this party."

That's on Kathie Belgum's mind, too. She voted for Perot in '92 in hopes that he would build a viable third party. Now, the 71-year-old Iowa Citian is leaning toward Nader.

Belgum doesn't want to help elect Bush by voting for Nader, "but you have to vote for someone you believe in."

It's unlikely that Nader is the "cause of Al Gore's demise," said Andy Goldman, a Nader staff member.

"It's more likely that he's appealing to the 51 percent ofAmericans who don't vote," said Goldman, who called Gore "a phony progressive."

"We're not going to give up now because Gore realizes he's losing his base," Goldman said. "How can that be our fault?"

Nader urged young people in the audience to be as idealistic as the college students of the 1960s who demonstrated to end the Vietnam War, promote civil rights and stop pollution.

"They rolled up their sleeves and went to work," Nader said, adding that it is time for this generation of college students to "put your arm on the wheel of justice." Students in their 20s are at the "peak of their idealism," he said, and should use their time for "discretionary thinking" about the kind of world they want to build.

Nader also accused Gore and Bush of being tied to giant agribusiness corporations, calling himself the only candidate who would help family farmers. "The small farm economy is in its greatest historical crisis" and is being drowned by a "tidal wave of corporate agribusiness."

The Green Party candidate said agribusiness is just another example of the ties Gore and Bush have with corporate interests, further defining the need for a viable third-party movement. "When it comes to corporate power, the only difference between Al Gore and George W. Bush is the velocity with which their knees hit the floor when corporations knock on their door," Nader said.

The Associated Press contributed to this story.