Support for Proposition 30, Gov. Jerry Brown’s initiative to raise income taxes on the wealthy sales tax, has decreased since May, according to the latest USC Dornsife/Los Angeles Times Poll.

Fifty-five percent of registered voters reported support for the measure, down from 59 percent last May. The September poll shows that 36 percent oppose the initiative and 9 percent remain undecided.

“From looking at the results of this poll, while the Governor’s initiative is still passing, it remains very vulnerable,” said Dan Schnur, director of the Jesse M. Unruh Institute of Politics at USC.

According to Schnur, the last time people voted to impose tax increases on a majority of the population was in 1993.

Polling results also showed that the strongest support for Prop. 30 comes from the 18 to 29 age group.

Makana Krulce, a sophomore majoring in chemical engineering, said she believes that Prop. 30 is a fair way to ease some of California’s financial pain.

“Low-income groups are suffering the most right now, so I feel that the wealthy should have to pay their fair share to fix our state’s problems,” Krulce said. “Also, if Californians take personal responsibility for some of the deficits, there will be less budget cuts to important programs, like education.”

Proposition 38, millionaire Molly Munger’s initiative to increase state income taxes for public schools, early childhood development programs and debt reduction, is supported by 34 percent of voters and opposed by 52 percent, according to the poll.

Schnur said that at this margin, it is rare for a proposition’s support to increase enough to pass by Election Day.

The poll also asked voters about how satisfied they were with new changes to the pension system that were recently signed into law by Brown. The changes included limiting pensions for new employees and raising the retirement age. Forty-five percent of voters said that the new law is a good start, but 39 percent feel that the new measures do not go far enough.

The poll surveyed more than 1,500 registered voters from Sept. 17-23. All polling was conducted by bipartisan interviewers to ensure unbiased results. The newest poll’s margin of error was 2.9 percent, according to Schnur.

The poll also surveyed opinions on several other issues, including propositions to change laws concerning criminal justice and genetically modified food.

The latest poll found that Californians favor Proposition 36, which would reform the three-strikes law to make it more lenient. According to the poll, 66 percent of registered reporters support the measure and 20 percent oppose it.

“Californians are looking for ways to save money and imposing shorter sentences on non-violent offenders appears to be a reasonable way to reduce prison costs,” Schnur said in a statement. “The challenge for the initiative’s opponents is to convince voters that prisoners who have previously committed violent crimes are still dangerous, but that looks like an uphill fight at this point.”

When it came to banning the death penalty, however, respondents to the poll were less open to change.

According to the poll, Proposition 34, a measure to eliminate the death penalty is supported by 38 percent of registered voters and opposed by 51 percent.

The poll also discovered that 61 percent of registered voters support Proposition 37, which would require labeling for foods with genetically modified ingredients. Twenty-five percent of registered voters oppose the measure and 14 percent said they were undecided or did not answer the poll.

“Something called genetically modified food sounds really scary, so it’s not surprising that the support for [Prop. 37] is this large,” Schnur said to the Los Angeles Times.