SACRAMENTO — A Field Poll released Friday suggests trouble for supporters of California ballot propositions seeking to overturn the state’s greenhouse gas protections and legalize marijuana for recreational use.

The survey found that 48 percent of likely voters oppose the marijuana initiative, while 44 percent support it. That’s far from the level of support typically needed at this stage of a campaign, said Mark DiCamillo, the poll’s director.

“When you’re starting out behind, the odds are against you, so that’s going to be a tough one to pull off,” he said.

Proposition 19 would allow adults to cultivate marijuana and enable local governments to regulate and tax sales of the plant to raise revenue. Proponents have said the proposal could generate $200 million per year, but others say the amount would be lower. California already allows marijuana use for medicinal purposes.

Voters also are skeptical of an oil-company-funded initiative, Proposition 23, that seeks to suspend the state’s landmark global warming law. Just 36 percent support the effort, while 48 percent are opposed.

DiCamillo said both initiatives face difficulties, because propositions with less than 50 percent support early in the campaign tend to lose. They are among 10 propositions that will appear on November’s general election ballot.

Backers of Proposition 23 dismissed the poll’s results as irrelevant. “The only thing this so-called ‘poll’ illustrates is that the majority of voters have not heard about Prop. 23,” said John Kabateck, executive director of the National Federation of Independent Business/California. He is a co-chairman of the Proposition 23 campaign.

Steven Maviglio, a spokesman for the no-on-23 forces, was jubilant. “Even with their Texas-sized checkbooks, oil companies Valero and Tesoro will have a difficult time convincing Californians to support their deceptive ballot measure that will effectively kill clean air and energy standards,” said Maviglio, of the group Californians for Clean Energy & Jobs.

Other opponents of the measure include PG&E, the Silicon Valley Leadership Group and Gov. Arnold Schwarzenegger.

An $11.1 billion water bond placed on the ballot by Schwarzenegger and state lawmakers is favored by 42 percent of voters, although many had no opinion. The Republican governor recently urged lawmakers to pull the bond off the ballot, saying the state’s high unemployment rate and $19 billion budget deficit would hurt its chances of passing.

He wants to delay the vote until 2012, although the Legislature has not yet acted on his recommendation.

A wide majority of voters is supporting a proposition seeking to change the state’s budget process. Among likely voters, 65 percent said they would approve Proposition 25. The constitutional amendment calls for a simple majority vote in the state Legislature to approve a budget, rather than the current two-thirds majority. It retains the two-thirds threshold for raising taxes.

Just 20 percent would vote no on the proposition, while 15 percent remain undecided.

DiCamillo said support for the initiative has increased since January, perhaps because it also calls for docking lawmakers’ pay when a budget is late.

If voters approve the measure, lawmakers would permanently forfeit their salaries and daily expense reimbursements until they pass a budget.

The telephone survey of 1,005 likely voters was conducted June 22 to July 5. It has a margin of error of plus or minus 3.2 percentage points and a higher margin for subgroups.