Two key senators are rolling out a bipartisan amendment on background checks for gun buyers.  Democratic Senator Joe Manchin of West Virginia and Republican Senator Pat Toomey of Pennsylvania say the measure would expand criminal checks to include sales made at gun shows and online.  It's aimed at closing loopholes in the existing law without affecting other private sales.  

Senator Manchin said the amendment does not infringe on the rights of gun owners.  He called it "a first step" toward finding common ground to keep guns out of criminal hands and to help keep children safe.  The bipartisan agreement may boost prospects for the passage of a gun control bill.  The Senate is set to hold its first test vote on the issue Thursday.