Oil is becoming a major issue in the surprisingly tight U.S. Senate race in North Carolina between incumbent Republican Elizabeth Dole and Democratic challenger Kay Hagan. But it’s also apparently a financial consideration for the senator, despite her claims to the contrary.

Dole’s husband, former Senate majority leader and 1996 Republican presidential candidate Bob Dole, has at least $1 million invested in an offshore Lehman Brothers hedge fund that invests in oil, gas and natural gas, Politico reports, citing Senate financial disclosures.

Dole has attacked Hagan, a North Carolina state senator, for her investments in oil wells and oil stocks. The senator also claimed that neither she nor her husband “own oil stocks,” which is technically true. But the couple did earn between $51,000 and $100,000 last year from their investment in the Lehman hedge fund, Strategic Commodities II.

Dole’s campaign, however, is sticking by its story, arguing that the first-term senator does not profit “directly from the increase in gas and oil prices.”

Recent polls show Hagan trailing Dole by less than 10 points, with the incumbent receiving less than 50% support.