California billionaire Tom Steyer turned heads in Washington with the news that he plans to spend $100 million to help make climate change a defining issue in this year’s elections.

But it gets even bigger: The hedge fund executive turned green activist might be willing to lay out even more than that eye-popping number, and he’s looking to spend it in places that are also important for 2016.

Steyer’s strategy calls for targeting races including Senate or gubernatorial contests in Iowa, New Hampshire, Florida and possibly Pennsylvania — all key battlegrounds in presidential politics, sources familiar with the plan said on Tuesday.

The fleshed-out details paint a picture of a big-pocketed donor who is going beyond his early efforts to help individual Democrats, such as Massachusetts Sen. Ed Markey and Virginia Gov. Terry McAuliffe, as well as address specific issues like the Keystone XL pipeline — and instead wants to give his signature climate cause a starring role in the next presidential race.

Steyer’s operation “is going to be very aggressive” and will set itself apart from the efforts of mainstream environmental groups, said Betsy Taylor, a Takoma Park, Md.-based leader of a network of wealthy climate donors who attended a recent discussion of the strategy at the billionaire’s California ranch. “They’re fearless. They don’t worry about access to Democratic Party leadership.”

Steyer isn’t publicly saying much about how he’ll spend of his projected campaign war chest through his NextGen Climate Action super PAC, which The New York Times first reported Monday. The strategy could make him a progressive counterweight to big conservative donors like Charles and David Koch. But it’s unclear how far even $100 million will go in the post-Citizens United world, or whether global warming can compete on the presidential campaign trail with issues like jobs and President Barack Obama’s health care law.

Still, Steyer has told potential backers he has big plans. Those include trying to influence the debate about climate change in Senate races in Iowa and New Hampshire and the gubernatorial contest in Florida.

He may also spend money influencing the governor’s race in Pennsylvania, where one of the Democrats vying to unseat Republican incumbent Tom Corbett is former Bill Clinton environmental aide Katie McGinty.

In addition to looking ahead to 2016, Steyer’s strategy includes focusing on states where a candidate who supports acting on climate change faces an opponent who’s a “denier.”

That description matches the governor’s race in Florida, where Republican Gov. Rick Scott’s top challenger is Democratic former Gov. Charlie Crist, and the Senate race in Iowa, where Democratic Rep. Bruce Braley and several potential Republican challengers are vying to replace retiring Democrat Tom Harkin.

While Scott has said he doesn’t believe that science has proven that humans are causing climate change, Crist used to hold annual conferences on global warming when he was governor and was a loud critic of BP during the 2010 Gulf of Mexico spill. And Crist may need all the financial help he can get: Scott, a former hospital chain executive, is planning to spend as much as $100 million for his reelection effort, possibly enough to match Steyer’s entire nationwide campaign.

Besides being a notoriously tight swing state, Florida is a prime example for climate advocates of how sea-level rise can threaten communities.

Steyer also wants to target states that are significant in determining whether Democrats can keep the Senate this year. Those include Iowa and New Hampshire.

And he wants to sway governor’s races in states where the winner could move ahead with action on climate change without waiting for Washington. That could point toward jumping into Pennsylvania to help McGinty, who chaired the White House Council on Environmental Quality under Clinton, or other Democratic gubernatorial candidates.

Steyer and his PAC’s chief strategist, veteran Democratic operative Chris Lehane, outlined the approach during a gathering of wealthy climate donors at the ranch during the first weekend of February. Columbia University climate researcher James Hansen, former head of NASA’s Goddard Institute for Space Studies, was on hand to give a briefing on potential climate change effects in the years and decades ahead. The gathering also included fellow billionaires and some of Steyer’s oldest friends from the financial community.

“There were definitely some heavy hitters there,” Taylor said.

The New York Times first reported Monday that Steyer’s goal is to spend about $50 million of his own money and raise another $50 million from green-minded donors to use in 2014. NextGen officials confirmed those figures Tuesday but stressed that $100 million is not the ceiling for what Steyer’s PAC may spend this year.

They noted that Steyer has already spent more than $50 million on his climate-related campaign efforts. Those include pushing a successful 2012 ballot initiative in California to direct money generated from closing tax loopholes to clean-energy efforts; last year’s winning campaigns by Markey and McAuliffe; and a local election in Washington state that was central to efforts to oppose a coal exporting facility.

“And he has made clear he intends to ramp up for 2014, which is a pivotal year politically for climate,” a NextGen official said by email.

Taylor was optimistic about at least reaching the $100 million goal.

“I think he’s going to raise it,” she said. “There were some big pockets at his ranch, and there are a lot of other people out there who I think are realizing that we’re out of time on the climate fight.”

Steyer was speaking “to his core team” during that weekend, but he and Lehane are casting a wider net as well, she said.

Climate donors have praised Obama’s climate strategy, including the Environmental Protection Agency’s landmark rules on power plant emissions and U.S. efforts to reach a global climate pact in Paris next year. But many stress that it isn’t enough — hence the focus on what states can do and on getting more friendly voices in Congress.

Steyer’s efforts may overlap with races that traditional environmental groups like the League of Conservation Voters and the Sierra Club could target, including the open Senate seat in Michigan.

Taylor said Steyer specifically mentioned the Florida, Iowa and New Hampshire Senate races during the gathering. She declined to further detail the list but said that “they’re going into several places, and they’re still talking to candidates.”

Steyer will have plenty of time to talk politics Wednesday, when his San Francisco home will play host to a fundraising dinner for the Democratic Senatorial Campaign Committee that will feature several Senate Democrats, including Majority Leader Harry Reid, according to an invitation obtained by POLITICO. The seven Democrats expected at the dinner include three up for reelection this year: Jeanne Shaheen of New Hampshire, Mark Udall of Colorado and Jeff Merkley of Oregon.

Shaheen may have a tough race, especially if former Massachusetts Republican Sen. Scott Brown challenges her, while Udall is expected to face a stiff challenge from GOP climate skeptic Ken Buck. Reid’s appearance is notable as he tries to help Democrats cling to control in the Senate.

During the event, Steyer will give his guests a preview of a poll he financed regarding the Keystone XL pipeline, which he plans to publicly release Thursday. The survey examined the public’s attitude toward Chinese investment in the Canadian tar sands, as well as whether the oil sent by the pipeline should stay in the United States and how that affects support for Keystone, NextGen officials said.

Late this week, Steyer will attend the Democratic Governors Association’s meeting in D.C. and moderate a panel there with governors and private-sector executives about how states can work together to address climate change, NextGen officials said. That includes highlighting regional greenhouse gas initiatives like one that exists in New England.

Despite the huge pile of dollars Steyer may wield, it’s unclear how many important races will meet the criteria he has set out. He clearly faces a tougher challenge than he did in 2013, when he helped Markey win in blue Massachusetts and helped defeat the tea party-aligned Ken Cuccinelli in the Virginia governor’s race.

For one thing, many of this year’s most crucial races involve Democrats trying to retain control of the Senate by winning tight contests in politically red states. But the Democrats running in Alaska, Louisiana, West Virginia and Kentucky have sought to distance themselves from the Obama administration’s energy policies and either support Keystone or have criticized EPA greenhouse gas regulations.

Steyer would be hard-pressed to help any of them — and has even threatened to go after Sen. Mary Landrieu (D-La.) for her support of Keystone.

Steyer hasn’t yet promised to pull the trigger on targeting Landrieu. In fact, an attack from Steyer’s group could help her by showing she doesn’t march in lockstep with her party’s liberal wing.