Senate Majority Leader Harry Reid, D-Nev., is reportedly falling short of the 60 votes needed for the bipartisan background checks compromise, and Vice President Joe Biden is stepping in to try and save the measure.

Democratic aides told Politico that a whip count was done on Monday. Now Biden is making personal calls to senators urging them to back the measure, that website reported.

Sens. Joe Manchin, D-W.Va., and Pat Toomey, R-Pa., agreed to the compromise last week to expand background checks to gun shows and online sales so that criminals and the mentally ill don’t get their hands on firearms.

Last week, two Democrats defected and joined with Republicans' attempt to block debate on the gun control bill. However, the measure ended up passing 68-31 when 16 Republicans voted to end a Republican-mounted filibuster to proceed with a debate on the 2013 measure.

About four Republicans have indicated they are considering voting for yes on the background checks proposal. They are Sens. John McCain of Arizona, Mark Kirk of Illinois, Susan Collins of Maine and Kelly Ayotte of New Hampshire.