A slim majority of voters support Proposition A, the half cent sales tax increase on the ballot Tuesday, according to a USC/L.A. Times poll released Saturday.

The poll surveyed 500 likely voters on the tax hike. City leaders say Proposition A, which would boost the city's sales tax to 9.5 percent--one of the highest in the state--will fund police, parks and other basic services.

The poll found 53.4 percent of voters definitely or probably support the tax hike, while 40.6 percent are against it. Six percent of voters said they were undecided.

The proposition needs a simple majority to pass.

"Although measure A is ahead in our poll, the fact that it's so close to the 50 percent threshold puts it in a very precarious position," USC's Dan Schnur, director of the poll, said in a statement.

Supporters include Mayor Antonio Villaraigosa, City Council President Herb Wesson, and real estate development companies, such as Anschutz Entertainment Group, owner of the Staples Center.

Developers, billboard companies and unions are heavily funding pro-Proposition A advertisements. In television and web spots, LAPD Chief Charlie Beck and Maria Elena Durazo, head of the Los Angeles County Federation of Labor, urge voters to approve hike.

Opponents include all the mayoral candidates. Councilman Eric Garcetti has said he believes the L.A.'s finances aren't as dire as portrayed by City Hall's budget analysts.

The same poll also weighed in on the City Attorney's race. Former Assemblyman Mike Feuer has a lead of 23.8 percent, while 16.4 percent back current City Attorney Carmen Trutanich. The poll also showed 15.2 percent of voters support attorney Greg Smith, and 4.7 percent back attorney Noel Weiss.

The polls were conducted Feb. 24-27. The margin of error is 4.4 percentage points.

USC Price/LA Times will release a poll Sunday on the L.A. mayor's race.

dakota.smith@dailynews.com