U.S. Rep. Russ Carnahan, throwing more jabs in an increasingly acrimonious re-election fight, is going after his opponent for ownership in oil companies.

Financial disclosure forms submitted recently by Republican Ed Martin, who is hoping to thwart Carnahan's bid for a fourth term, show that his wife owns tens of thousands of dollars of stock in Exxon Mobil Corp. The notoriously vague congressional forms do not provide an exact count of her holdings, but it is between $100,001 and $250,000.

The Carnahan campaign is using Martin's family holdings in oil to slam his views on the spill in the Gulf. Martin believes the oil rig disaster was the product of too much -- and not too little -- government regulation.

"Letting Big Oil drill without oversight in the wake of this disaster is a position that defies logic – unless you realize that bigger profits for Big Oil would directly benefit Ed Martin’s bank account," Carnahan campaign Angela Barranco said in a statement.

Though Exxon is the families single largest holding, Martin's wife, a physician, owns shares in Intel, GE, McDonald's, Disney and Coca-Cola, as well. Carol Martin also owns between $1,001 and $15,000 in Chevron stock, though that appears to be part of a Roth IRA.

Martin does not have any stake in BP, which is good for him -- not only would it be a political liability, but shares in the company have tumbled by more than 50 percent in the last three months.