Sen. Ben Nelson (D-Neb.) sought to debunk “wild speculation, unfounded rumor and uninformed comments” about his opposition to starting Senate debate on financial regulatory reform.

Nelson, who again voted against proceeding to the measure Wednesday, countered accusations that his opposition arose after a provision that could have benefited Nebraska billionaire Warren Buffett was dropped.

“To be absolutely clear, I did not vote no because of Berkshire Hathaway,” Nelson said in a statement referring to Buffett’s Omaha-based company.

Nelson, who joined Republicans in voting against procedural motions brought up on Monday and Tuesday, also denied that his stock ownership in Berkshire swayed his position. Rather, Nelson has told reporters in recent days that his concerns lie with auto dealers and dentists, who the Democrat fears will be adversely affected by legislation being pushed by Banking, Housing and Urban Affairs Chairman Chris Dodd (D-Conn.).

“I have heard from Nebraska business owners and leaders that the underlying bill will extend too far and adversely impact Main Street businesses that use third party financing to help customers pay for their products or services,” Nelson’s statement explained.

Nelson also circulated a letter from the Coalition for Derivatives End-Users, a group of more than 200 businesses, that criticizes language in the Senate bill focusing on over-the-counter derivatives. Derivatives are complex financial instruments in which investors bet on the future price of commodities or other financial products.

Berkshire Hathaway did not sign on to the letter, although ConAgra Foods, another Nebraska-based company, did.

Nelson similarly became a center figure during the health care reform debate last year, when he was roundly criticized for securing the “Cornhusker Kickback,” a provision — later dropped — that would have guaranteed the federal government would pick up the tab for the state’s new Medicaid expenses.