This post has been updated.

Timothy M. Kaine (D) has bought an additional $3 million worth of airtime in his U.S. Senate contest against George Allen (R), as the conservative group Crossroads GPS continues its assault against the Democrat with a new ad.

Kaine’s campaign announced Tuesday that it had purchased the additional time, bringing its total buy through Election Day to $7.5 million. Allen has booked at least $5 million in airtime through October, though both campaigns could choose to spend more cash this month.

Crossroads continues to shell out money too, unveiling a spot accusing Kaine of being bad for small businesses.

“Tim Kaine supports cap and trade, a huge tax and a big job-killer.,” the ad’s narrator says. “The scheme Kaine backs could increase energy costs for small businesses by 40 percent. ... Higher taxes, fewer jobs. Tim Kaine: Bad for small business, too liberal for Virginia.”

Crossroads said it was spending a total of $1.2 million to air the Virginia ad. The group is also targeting Democratic Senate candidates in several other states.

As has been the case with past Crossroads ads, the Kaine campaign called the new spot highly misleading. The Democrat has a “strong record” of helping small businesses, Kaine spokeswoman Brandi Hoffine said.

And the campaign noted that PolitiFact Virginia rated another ad leveling a similar charge on cap and trade against Kaine to be “Mostly False.” ( PolitiFact noted that “the assertion that cap and trade leads to higher energy prices is reasonable but depends on the specifics of a plan.”)

“As a senator, Tim Kaine with work with both sides of the aisle to address the growing challenge of climate change in a responsible way that protects our economy and addresses concerns from our defense community,” Hoffine said. “In contrast, how can we expect George Allen to contribute to a solution when he doesn’t believe there is even a problem?”

This story has been updated.