LOS ANGELES, AUG. 27 -- Support for the nation's most ambitious environmental initiative, once thought headed for an easy victory on California's November ballot, has been weakened by a well-funded opposition campaign and has only an even chance of passing, according to a new Los Angeles Times poll.

The poll released Sunday shows Proposition 128, also known as "Big Green," drawing 44 percent support with 42 percent opposed, a virtual dead heat. The poll of 1,586 registered voters said 14 percent were undecided. A Times poll in late June showed the measure leading 46 to 38 percent.

An opposition spokesman said support for Proposition 128 suffered from two radio commercials linking the initiative to Assemblyman Tom Hayden (D-Santa Monica), Big Green campaign chairman and a former antiwar activist unpopular with many conservatives.

The poll said that voters' impression of Hayden is "5 to 3 negative" and that the agriculture, chemical and business interests opposing Prop. 128 had scored in calling it "the Hayden Initiative."

Don Schrack, spokesman for the "No on 128" campaign, welcomed the results and said that, although defeat of the initiative is not assured, "we are really in the driver's seat now."

Duane Peterson, press secretary for the "Yes on 128-Big Green" campaign, shrugged off the poll results, saying voters would support the initiative "once they see that we are the Sierra Club and the National Wildlife Federation and they are Dow and Monsanto."

The opposition took its radio commercials off the air last week after the Los Angeles city attorney filed a lawsuit charging that the spots illegally failed to mention sponsorship by the chemical industry.

Peterson noted that an initial Times poll question seeking voters' impression of the initiative found that nearly half had no opinion while the rest responded favorably by 2 to 1.

The sharp split in opinion occurred only after voters were read a 157-word statement saying the initiative "would ban cancer-causing pesticides in foods, prohibit new offshore oil drilling in state waters, establish measures against global warming and prohibit redwood tree logging" as well as "create a new elective post of state environmental advocate to enforce this initiative."

Voters also were told that "opponents say the measure contains too many important issues in one initiative" and "would cost state and local governments at least $3 billion." The statement ended by saying opponents "remind voters that the initiative was co-written by Tom Hayden, and they say he wants the position of environmental advocate for himself."

Peterson said the statement did not convey the "we-they thing" -- his campaign's emphasis on the near-unanimous support for the initiative from major environmental groups and the opposition's reliance on support from the chemical and agricultural industries.

The Yes on 128 campaign has broadcast a television commercial, predominantly in Los Angeles, portraying a child wandering in traffic as a symbol of dangers to the environment. The No on 128 radio spot, which emphasized the Hayden connection and the theme of an initiative that "tries to do too much," was heard frequently in all major markets.

The Times poll revealed a sharp urban-rural split, with voters in the Los Angeles and San Francisco areas supporting Big Green while other voters -- particularly those in the Central Valley where the pesticide restrictions could affect farmers -- were generally opposed.

Democratic gubernatorial candidate Dianne Feinstein has been warned recently by Central Valley Democrats that she could lose her close race with the GOP candidate, Sen. Pete Wilson, a Prop. 128 opponent, because of farmers' distaste for her support of Big Green.