The California State Assembly on Tuesday voted 43-32 on a bill that aims for 100 percent renewable energy by 2045, one of the nation's toughest clean energy mandates.

Should the bill become law, California has to entirely transition away from fossil fuel electricity in less than three decades. Utilities would also have to get 50 percent of their energy from solar, wind or other specific renewable sources by 2026 and 60 percent by 2030. The legislation requires the state to slowly transition away from natural gas, which is California's top electricity source.

Senate Bill 100, introduced by Sen. Kevin de León, (D-Los Angeles), was approved in the Senate last year. Both chambers now must agree on amendments, but it is expected to be finalized by Friday before heading to Gov. Jerry Brown's desk for approval. The Democratic governor is poised to sign it into law, The New York Times reported.

"I will always work for the people of California, and the future, [that's] why I authored this bill. And after a grueling year it has finally passed. And our state will remain a climate change leader in the world," de León, who is running for U.S. Senate, tweeted Tuesday.

The passage comes less than two weeks before the Rise for Climate, Jobs, and Justice mobilization in San Francisco on Sept. 8 and the Global Climate Action Summit from Sept. 12-14, where Gov. Brown will serve as co-chairman.

The first state to adopt such an aggressive clean energy standard was Hawaii in 2015, calling for 100 percent carbon-free electricity by 2045.

The Golden State's move is considered groundbreaking because it could inspire other governments and spur Massachusetts, New Jersey, New York and Washington, DC, to consider similar pending legislation.

If signed, California will represent the largest global economy and one of the biggest states of any kind in the world to have a goal of moving to 100 percent clean energy, the Sierra Club noted.

"This is a pivotal moment for California, for the country, and the world, Michael Brune, executive director of the Sierra Club, said in a statement. "While Donald Trump abandons reality by ignoring the climate crisis and the incredible growth of clean energy, California is stepping up to lead the transition to a 100 percent clean energy economy."

Opponents of the initiative include Pacific Gas and Electric Company, San Diego Gas & Electric Company, Western States Petroleum Association, Agricultural Council of California and more than two dozen others, The Sacramento Bee reported. Some lawmakers worry the bill could hurt fossil fuel workers and raise utility prices.

"We pass all these goals for renewables, but at the same time our families back home will pay the cost with an increase in the electric bills every year as we try to achieve this," Assemblyman Devon Mathis, R-Visalia, told the publication.

The bill was praised by most Democrats, green organizations and high-profile environmental activists, including Vice President Al Gore, actor and former Gov. Arnold Schwarzenegger, Leonardo DiCaprio, Chris Hemsworth and Mark Ruffalo.

"With wildfires intensifying and temperatures skyrocketing, the impacts of climate change across the Golden State are impossible to ignore," 350.org executive director May Boeve said in a statement. "Just this week, the state's own climate assessment revealed that climate change will be deadlier, more destructive, and costlier than previously thought. SB 100 is a critical first step toward addressing the worsening climate crisis, but to truly change course, we must end fossil fuel extraction."