Republican gubernatorial candidate Ken Cuccinelli, left, gestures during a debate with Democratic challenger Terry McCauliffe during the Virginia Bar Association convention debate at the Homestead in Hot Springs, Va., on July 20. (Steve Helber/AP) (Steve Helber/AP)

The advertising arms race keeps escalating in Virginia’s contest for governor, with a trio of ads on the air helping Attorney General Ken Cuccinelli II (R) even as a deep-pocketed environmentalist will begin funding attacks on the Republican nominee.

Cuccinelli launched a new ad Monday criticizing Democratic nominee Terry McAuliffe, and the Republican Governors Association is up with a pair of spots also hitting McAuliffe. They will soon be joined on the air by billionaire financier Tom Steyer, who plans to pour money into the commonwealth because he dislikes Cuccinelli’s stances on environmental issues, including coal and climate change.

A spokesman for Steyer said his initial ad buy would be for roughly $400,000 and that he will be paying to keep on the air an existing McAuliffe ad that accuses Cuccinelli of conducting a “witch hunt” against former University of Virginia climate scientist Michael Mann. Steyer is a major supporter of clean energy projects, and he told Politico, which first reported on his Virginia plans, that he believed there was “a very clear choice” between Cuccinelli and McAuliffe on climate issues.

Cuccinelli spokeswoman Anna Nix called Steyer a “radical environmentalist” who supported a “war on coal.”

“It’s no surprise Terry McAuliffe is depending on yet another rich, national Democrat — instead of grass-roots support from Virginians — in his campaign for governor,” Nix said.

Cuccinelli, meanwhile, is focusing in his latest ad on GreenTech, the electric car firm co-founded by McAuliffe that faces a Securities and Exchange Commission investigation. The company is also part of a separate probe by the Department of Homeland Security’s inspector general into whether a top immigration official improperly helped GreenTech and a sister firm obtain visas for foreign investors. The Cuccinelli spot centers on that investigation.

“It’s time for Terry McAuliffe to tell us the truth,” the ad concludes.

McAuliffe spokesman Josh Schwerin said Cuccinelli “is launching another misleading attack on Terry McAuliffe because he doesn’t want to discuss his own extreme agenda and refusal to repay Jonnie Williams and Star Scientific for $18,000 in gifts and trips,” as well as other controversies.

The RGA is also making its presence felt in Virginia. According to filings made public by the Virginia Public Access Project, the RGA has spent more than $700,000 on air time in the state. The group is airing two ads hitting McAuliffe, who has consistently raised more cash than Cuccinelli in the governor’s race.

The latest RGA ad, “Shift,” was released Sunday and says McAuliffe is “falsely attacking Ken Cuccinelli on energy.” The ad invokes GreenTech and concludes: “Terry McAuliffe, you just can’t trust him.”

The RGA spot appears designed to defend Cuccinelli against criticisms leveled by McAuliffe and his fellow Democrats over the attorney general’s office’s handling of an ongoing legal dispute over natural gas royalties in Southwest Virginia. A federal judge has criticized the actions of a lawyer in Cuccinelli’s office for “assisting” two energy companies involved in the case, though the attorney general’s office has said the lawyer did nothing improper.

Schwerin said the ad demonstrated that Cuccinelli and “his Washington backers” were “panicking about the ongoing scandal over Cuccinelli siding with out-of-state energy companies in their lawsuit against Southwest Virginians.”

Another RGA ad released last week focuses more specifically on GreenTech, particularly on whether the car company is really building cars and creating jobs in the U.S. as McAuliffe pledged. The spot also ends by saying “you just can’t trust” McAuliffe.