By Andy Sullivan
WASHINGTON (Reuters) - New York Mayor Michael Bloomberg predicted on Sunday that pressure from the American public would eventually force the Congress to expand background checks for gun buyers, even though the measure faces an uncertain fate in the Senate.
As Bloomberg launched a $12 million national advertising campaign aimed at prodding members of the Senate to support expanded background checks, he said the measure's widespread popularity would trump gun-rights groups like the powerful National Rifle Association that oppose it.
"If 90 percent of the public wants something and their representatives vote against that, common sense says they are going to have a price to pay for that," Bloomberg said on NBC's "Meet the Press."
A top NRA executive predicted that the self-made billionaire' s efforts would change few minds. "He can't buy America," NRA executive vice president Wayne LaPierre said on the same program.
Lawmakers are scaling back President Barack Obama's ambitions for sweeping gun control measures, which took on a new urgency after the December 14 school shooting in Newtown, Connecticut, that killed 20 children and six adults.
Gun-control advocates say a system of expanded background checks would be the single most effective way to reduce gun violence across the country. Opinion polls show that more than 90 percent of all American voters and 85 percent of gun owners support it.
While such a measure could pass the Democratic-controlled Senate, it faces long odds in the House of Representatives, where Republicans hold the majority.
"I don't think their bill will pass the Senate and even if it does it won't pass the House," Republican Senator Tom Coburn said on C-SPAN.
The NRA argues that expanding existing background checks to cover the 40 percent of gun sales that are now exempt would only create more hurdles for law abiding citizens and do little to deter criminal purchases. The NRA instead wants the federal government to step up prosecutions under existing gun laws and boost security in schools.
Bloomberg acknowledged that a national ban on assault weapons is less popular with the public and is unlikely to succeed in Congress.
Several states, including New York, have passed assault-weapons bans of their own but others like Colorado, which tightened its gun laws recently, have not restricted the military-style rifles that are popular with gun owners.
"I think the feeling right now around assault weapons, at least in Colorado, is that it's so hard to define what an assault weapon is," Colorado Governor John Hickenlooper said on CNN's "State of the Nation."
"There's a lot of questions whether the 10-year federal ban that existed made a difference," Hickenlooper said. "It's a tough sell."
(Additional reporting by David Brunnstrom and Toni Clarke. Editing by Christopher Wilson)