House Majority Leader Eric Cantor is attacking his GOP primary opponent with a new television ad, a highly unusual move for a sitting member of House leadership that demonstrates he is taking the threat from his right back home more seriously than past months.

The ad criticizes his opponent, Randolph-Macon economics professor David Brat, for a tangential association with former Democratic Gov. Tim Kaine, who proposed raising taxes while he was in office. But a top Virginia official says the association is fleeting at best.

“College professor David Brat is running against our conservative congressman Eric Cantor,” a narrator reads to kick off the ad. “But Brat worked on Democratic Gov. Tim Kaine’s Council of Economic Advisors while Kaine tried to raise our taxes by over $1 billion on cars, insurance and income. Now, liberal David Brat is running for Congress as a Republican. Liberal college professor? Tim Kaine adviser? Republican? Come on professor, you’ve got to be kidding.”

In 2006, Kaine appointed Brat to the state’s Joint Advisory Board of Economists, comprised of academics, businessmen and one member from the Federal Reserve Board. Brat served on the board through the rest of Kaine’s term.

Virginia Secretary of Finance Ric Brown, an economist who has served in various capacities for the Virginia government since 1971 and has been appointed by both Republicans and Democrats, said the board had nothing to do with setting tax policy at all.

“The charge of the Joint Advisory Board of Economists is to come up with basically a consensus economic forecast for both Virginia and the nation,” Brown said in a phone interview. “At their meetings, they do not deal with revenue estimates. They deal with economic variables–unemployment, personal income, wages and salaries, cost of living–nationally and at the state level. They try to come up with a consensus forecast.”

“They don’t deal with revenues but there is another advisory board–the Governor’s Advisory Council on Revenue Estimates, that he [the governor] chairs with major CEOs that do business in the state of Virginia–they deal with preliminary revenue forecasts that are derived from the economic forecasts that come out of the Joint Advisory Board of Economists meetings,” Brown added.

Brat, who expressed anger at what he described as the ad’s inaccuracies, noted that Cantor ad buy shows he is treating the race seriously.

“The Cantor Team says we have no race but out comes a negative ad,” Brat said in an email. “Don’t have to be a political genius to do the math on this one.”

Besides his primary battle, Cantor is facing increasing criticism from the right for his actions as Majority Leader as speculation builds about whether Speaker John Boehner will return to Congress in 2015.