By SUSAN DAVIS

Facing an outcry at home in Nebraska for casting the critical vote in favor of a health-care overhaul, Sen. Ben Nelson has launched a new ad campaign to defend his position.

"I'm convinced this is right for Nebraska," says Sen. Nelson in the ad, which aired during the University of Nebraska's Holiday Bowl game Wednesday night and statewide Thursday. He says he took a "common-sense approach to improve the bill."

Mr. Nelson, who faces re-election in 2012, backed the Senate health-care bill only after lengthy talks in which he won agreement that the federal government would permanently cover the full cost in Nebraska of expanding Medicaid, the federal-state health program for the poor.

Getty Images

Sen. Nelson walks toward the Senate floor before a vote on the health-care bill on Dec. 24. Nebraska voters are dissatisfied with the senator as he agreed to back the bill after winning a Medicaid provision for his state.

Mr. Nelson's support was crucial for helping Democrats secure 60 votes for the bill, preventing a Republican filibuster.

Almost immediately, Mr. Nelson drew fire. Republicans have derided the bill as the "Nebraska Windfall." Sen. Lindsey Graham (R., S.C.) called it "sleazy." Even the state's governor, Republican Dave Heineman, has been critical of the deal.

In Nebraska, a Dec. 28 Rasmussen poll showed Mr. Heineman, who opposes the health-care bill, trouncing Mr. Nelson in a theoretical 2012 match-up, 61% to 30%. Mr. Nelson, who is 68 years old, was last re-elected in 2006 with 64% of the vote.

The reaction underscores possible political peril for Democrats as the battle over the health-care bill, which both parties now expect will pass, morphs into a battle of perceptions. A Wall Street Journal/NBC News poll in December found that by a slight margin, 44% to 41%, Americans prefer the health system as it is to the Democrats' health overhaul.

Democrats attribute that to negative publicity about relatively small parts of the bill, including the Nebraska Medicaid deal. They hope to redirect attention to the bill's main planks, such as the expansion of coverage to tens of millions of Americans and restrictions on insurance-company practices. Mr. Nelson's television ad reminds viewers that the bill would bar insurers from denying coverage over pre-existing conditions.

Republicans say the Nebraska provision is typical of what they describe as a bill stuffed with taxes, regulations and special-interest giveaways. They say Americans already understand what's in the bill and don't like it.

In Mr. Nelson's home state, the Medicaid deal already has produced a tit-for-tat between him and Gov. Heineman. Mr. Nelson said he asked for the item only because the governor was worried about how the health bill's Medicaid expansion would affect the state's budget. "Sen. Nelson's view is all states should get the same deal," said Jake Thompson, a spokesman for Mr. Nelson. "If the governor doesn't want it, if he asks, Sen. Nelson will ask to have it taken out."

But a spokeswoman for Mr. Heineman, Jen Rae Hein, said the governor has in fact asked. She cited a Dec. 21 letter by the governor to Mr. Nelson saying "all special deals must be removed" from the health bill. "That includes the Nebraska provision," she said.

"That's a statement, not a request," Mr. Thompson countered.