CHICAGO, AUG. 15 -- Its creators call it art with a message. But when an AIDS awareness poster showing a man kissing a man and a woman kissing a woman was displayed today on city buses here, two politicians said freedom of speech had gone too far.

"Where will we draw the line in terms of this homosexuality-heterosexuality thing?" said city Alderman Robert Shaw, adding that he would introduce an ordinance banning the poster.

"Is anything going on in this country now {acceptable} under the guise of free speech?"

The posters depict three couples, each in a romantic kiss -- a pair of men, a pair of women, and a man and woman. About 80 of the posters were displayed on buses and at transit stations.

"Kissing Doesn't Kill: Greed and Indifference Do," reads the poster, created by a New York art collective. A version has appeared in the mass transit systems of both New York and San Francisco.

"It's our way of saying we're all affected by AIDS," said Gran Fury collective member Loring McAlpin. "We don't think it's advocating a homosexual lifestyle."

The posters were approved earlier this year and refusing to display them would violate the First Amendment protection of free speech, said Alfred Savage, executive director of the Chicago Transit Authority.

"Under the law, we have a requirement to post them," Savage said. "We have no jurisdiction over the content."

The transit authority was sued last year for refusing to post another AIDS awareness poster it deemed "too black-oriented."

After the suit brought by the American Civil Liberties Union, the authority began displaying the ads, said John Hammell, who directs the ACLU's AIDS and Civil Liberties Program in Chicago.

Shaw said he planned to call a special City Council meeting to discuss his proposed ordinance, which would bar depictions such as that in Gran Fury's poster.

"This poster has nothing to do with the cure of AIDS," he said. "It has something to do with promoting a lifestyle, which I object to."

State Rep. Robert Regan (R) said Tuesday he would reintroduce legislation in the Illinois General Assembly that would bar such displays of sexuality. A similar bill failed this spring.

McAlpin said the poster, paid for by the New York-based American Foundation for AIDS research, overcame initial objections in San Francisco and New York. "Nobody said, 'This is great, we'll take it' -- there was a certain amount of resistance." The poster is intended to address the deadly virus "as an epidemic of corporate greed, government inaction and public indifference," McAlpin said. "We don't believe anyone is going to see that ad and change their sexual preference."