Green groups say their show of force behind Virginia gubernatorial candidate Terry McAuliffe is a preview of what's to come during the 2014 elections. [WATCH VIDEO]
McAuliffe has out-raised his Virginia Attorney General Ken Cuccinelli (R) by roughly $14 million with the help of hefty donations from environmentalists, and is favored to win Tuesday's election.
Activists say their support for McAuliffe is part of a larger effort to make climate change a major campaign issue.
"I think we have helped draw a clear contrast for voters in the race by prioritizing climate change issues," said Jeff Gohringer, spokesman for the National League of Conservation Voters.
The Virginia League of Conservation Voters contributed $1.7 million overall, making them McAuliffe's largest cash contributor outside of the Democratic Governor's Association.
"Terry is setting an example for other candidates that when they lean into these issues, they will be supported by a strong political force," Gohringer said to The Hill.
On Monday, the League released numbers on campaign funding that show environmental groups have outspent fossil fuel companies in the governor's race.
"Coal is no longer a winning wedge issue, and denying the problem of climate change and blocking action to address it is a much greater political liability," Navin Nayak, senior vice president of campaigns for the League, said in a memo.
The Sierra Club also donated to McAuliffe, a former Democratic National Committee chairman.
In total, the conservation group invested more than $500,000 in a campaign to defeat Cuccinelli.
Melissa Williams, national political director for the Sierra Club, said money from green groups has "absolutely" impacted the momentum in the race and might be a critical factor in the end.
"Huge investments from the environmental community have changed the narrative of this race and have elevated climate and clean energy issues in this race in a way they wouldn't have been without our investments," Williams said.
When asked if the Sierra Club plans to make this a trend in 2014 races, Williams said yes.
"The Sierra Club is looking to do this in the next cycle," Williams said. "We want climate to be an issue that candidates are forced to take a side on."
"We won't be in every state in 2014, but we will look to evaluate places where the Sierra Club can be decisive and where we can move the climate conversation."
McAuliffe ran a fierce attack ad strictly on climate change against Cuccinelli, the first candidate at this level to so, according to both the League of Conservation Voters and Sierra Club.
Cuccinelli's camp said McAuliffe showed he is "out of touch" with Virginians by turning to out-of-state money.
"Terry McAuliffe has courted and relied upon an unprecedented amount of out-of-state support from liberals like Michael Bloomberg and Tom Steyer who are counting on him to impose a big-government, radical agenda on Virginia workers and families," Cuccinelli spokeswoman Anna Nix said in an email to The Hill.
"If elected governor, Terry McAuliffe will put the interests of his liberal, out-of-state donors ahead of the people of Virginia. Ken Cuccinelli, on the other hand, has spent his entire life fighting for Virginians and putting their interests above his own," Nix said.
Steyer, a billionaire climate change activist, has spent more than $2.4 million on independent commercials blasting Cuccinelli through his political action committee, NextGen Climate Action.
Cuccinelli, portrayed as a "climate change denier" in McAuliffe's "Witch Hunt" ad, has taken a more traditional stance on coal and touted an anti-regulation agenda.
McAuliffe has voiced support for Environmental Protection Agency regulations on power plants, a top priority for green groups.
In the last week leading up to Tuesday's election, the League of Conservation Voters mobilized volunteers and knocked on 100,000 doors across the Richmond area, and 300,000 total in Virginia during the election cycle.
And Virginia's Public Access Project reported McAuliffe topped Cuccinelli in last-minute donations, 74,800 of which came from the Sierra Club.