Only 36 percent of 572 likely voters in the SurveyUSA poll taken between Tuesday and Thursday said they would certainly vote for Measure C. Because the proposal would raise the city of San Diego's hotel room tax rate to help fund the project, it needs support from two-thirds of voters to pass.
According to the poll -- taken on behalf of 10News and the San Diego Union-Tribune -- 23 percent of respondents were unsure. If all were to cast their votes for Measure C, the "yes'' side would still come up 7 percent points short of approval.
Another 41 percent of respondents said they would certainly vote against the measure. The poll has a margin of error of 4.2 percent.
Support for Measure C has declined since the last SurveyUSA poll, released Aug. 26. Then, the Chargers plans had the backing of 39 percent of respondents, with 36 against. A July check of public opinion showed 30 percent in favor and 40 percent against.
The release of the poll came five days after San Diego Mayor Kevin Faulconer endorsed Measure C. The mayor said he was taking a long-term view of the stadium issue and not just focusing on the November election. He said his backing came after Chargers Chairman Dean Spanos agreed to a series of protections for the city.
Majorities said neither Faulconer's endorsement nor the Chargers' on- field performance this season would make a difference in the way they vote.
No individual demographic in the latest poll reached the necessary 66 percent support, and the only one that came close was supporters of Measure D, which would guide the future course of tourism policy and determine the fate of the Qualcomm Stadium property should it be abandoned by the Chargers.
The only demographics to give Measure C even a simple majority were respondents who described themselves as "somewhat conservative,'' at 51 percent. Half of those who described themselves as Republicans favored the measure.
Measure D, by the way, had support from 32 percent of respondents and was opposed by 26 percent. Another 42 percent were undecided. Backers of the proposition contend it will become law with a simple majority next month, but City Attorney Jan Goldsmith said it required two-thirds because it also raises the hotel room tax.
While the chances are considered to be slim, there is a chance a court case elsewhere in California could do away with the two-thirds requirement for passing tax increases that begin as citizens initiatives. That would mean that Measures C and D would only need to get more than half the vote.
"The only way to truly defeat this billion-dollar-plus tax hike is to keep it below 50 percent on election day, so the No on C coalition is busy educating voters about the costs and risks of Measure C,'' coalition spokesman Tony Manolatos said. "Dean Spanos has spent more than $5 million trying to convince voters to raise taxes so he can build himself a rent-free stadium and a convention center annex Comic-Con is telling us not to build.''
The organizers of Comic-Con International, San Diego's annual popular arts extravaganza, say they prefer an on-site expansion of the current convention center over the Chargers project and the proposed convention center annex several blocks away from the center.
Besides Faulconer, Measure C has been endorsed by the San Diego Regional Chamber of Commerce. Opponents include the San Diego Taxpayers Association, Councilmen David Alvarez, Chris Cate and Scott Sherman, and Councilman-elect Chris Ward.
The Chargers did not comment on the poll.