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"Are there people who would be comfortable if there is a change in a definition? Is there an area that needs to be tightened up?" Manchin said recently. He and Republican Sen. Pat Toomey of Pennsylvania had negotiated the compromise plan.
The Senate defeated that plan for expanded gun background checks April 17 on a 54-46 vote, with 60 needed because of a threatened GOP filibuster. Five Democrats joined Republicans in opposition. The vote scuttled a watered-down version of the plan President Barack Obama proposed after the December massacre of 20 children and six school employees in Newtown, Conn.
A Democratic aide, who spoke on condition of anonymity, said the fresh effort is focused on senators including Republican Kelly Ayotte of New Hampshire, the only Northeastern senator to oppose the background check measure; Mark Pryor, an Arkansas Democrat; and Mark Begich, a Democrat, and Lisa Murkowski, a Republican, both of Alaska.
Manchin sent a letter Friday to senators who voted against the bill, asking for changes he should consider to win their future support.
"You don't just not continue working," he said.
Advocates want to gain enough support for a new vote before legislation to rewrite immigration laws and raise the federal debt ceiling dominate the congressional agenda in the next several months, the aide said. Senate Majority Leader Harry Reid probably won't bring up the proposal until Democrats have the 60 votes needed to advance legislation, the aide said.
Federal law requires a background check to buy a gun from a licensed dealer. The Manchin-Toomey amendment would require background checks for gun purchases over the Internet and between private parties at gun shows.
Polls have shown 90 percent of the public supports expanding background checks.
Manchin said one possible change would ensure that people who sell guns to relatives are exempted from background checks, even over the Internet.
The National Rifle Association maintains the expanded background checks would lead to a national gun registry. Federal law bars such a registry, and licensed gun dealers have kept sales records since 1968.