A month before Election Day, Sen. Mark R. Warner (D-Va.) has begun attacking his Republican rival with a television ad that plays on Ed Gillespie’s lobbying past.

“Enron. The largest corporate fraud in American history. And Ed Gillespie was their lobbyist,” the narrator says. News clips flash about the Enron employees who lost their jobs and savings and the executives who were sent to prison. With historical footage in the background, the ad tells viewers Gillespie was paid $700,000 to lobby for Enron. The Enron collapse happened in October 2001, and Gillespie’s firm cut ties with Enron in December of that year.

That dollar figure is derived from two Senate lobbying disclosures filed by Gillespie’s firm. He was one of four lobbyists registered as working with Enron.

The ad ends: “Enron’s Ed Gillespie. The million-dollar lobbyist who put Enron ahead of you.”

Warner is one of the safer Democratic incumbents facing reelection next month, but he’s still an incumbent in a swing state in an unfavorable environment for his party. A recent Quinnipiac poll gave Warner a nine-point lead over Gillespie, suggesting a narrower race than earlier surveys finding the Democrat ahead by double digits.

While Warner has brought up Enron in a debate and the Virginia Democratic Party has done so in billboards, this six-figure statewide ad buy is by far the senator’s most direct and substantial attack on Gillespie’s career as a lobbyist.

“This ad attacking Ed over a client company at his bipartisan firm 13 years and four jobs ago is the definition of hypocrisy, since it’s a company Warner himself owned stock in at the time,” Gillespie spokesman Paul Logan said. A 2002 Richmond Times-Dispatch article reported that Warner sold shares in Enron in 2001.

Gillespie has not been a registered lobbyist since 2007, when he left the bipartisan Quinn Gillespie & Associates for a job at the White House. Before launching his Senate campaign, he was running his own consulting firm, Gillespie Strategies. On the campaign trail, he has emphasized his college job as a parking attendant on Capitol Hill, not his career helping corporate clients navigate the place.

The Republican has begun launching his own attack ads, focused on Warner’s votes in support of President Obama in general and the Affordable Care Act in particular. The most recent ad, “Lie of the Year,” features video of the senator promising in 2009 not to support a health-care plan that would take away anyone’s current insurance.

“Mark Warner helped pass Obamacare, denying families the insurance and doctors we trust,” Gillespie says in the ad. “. . . I’ll replace Obamacare with market reforms that create jobs, hold down costs, and let us keep our insurance and doctors.”

The fact-checking Web site PolitiFact gave President Obama its “Lie of the Year” award in 2013 for repeatedly promising that people who liked their health-care plans could keep them. PolitiFact’s Virginia arm has since argued that it is inaccurate to apply the same label to Warner, an interpretation that Republicans dispute. Warner has pushed back on that barrage with his own ad labeling the attack “false” and saying he is working to fix health care.

Thus far, Warner has outpaced his opponent in fundraising and has outspent him 3 to 1 on TV ads. The two are scheduled to debate again Tuesday.