"I'm convinced this is right for Nebraska," Nelson says in the ad, according to the Journal-Star.
Nelson, whose reelection seems vulnerable at this early stage, has been pressured by Nebraska's Republican governor, prolife organizations and liberal advocacy groups for months.
The Journal-Star reported the ad will continue to air statewide after tonight.
The National Republican Senatorial Committee sent around the story and polls showing Nelson's support has declined.
"It's clear Ben Nelson is in full-scale damage control mode but when you consider that only 17% of Nebraskans support the Democrats' bill, it's hard to see how a TV ad is going to turn things around for him politically," said NRSC spokesman Brian Walsh. "In fact, it could arguably make things worse by serving to remind his constituents that he betrayed their values and the trust they placed in him."
Walsh added: "Ben Nelson may not be up until 2012, but this poll is a reminder about the serious peril facing other incumbent Democrats next year including Blanche Lincoln, Harry Reid and Michael Bennet, who also represent states in which the health care bill is similarly unpopular."