The co-sponsor of a measure aimed at expanding background checks for gun buyers is blaming the National Rifle Association for the bill’s defeat in the U.S. Senate this week. Senator Joe Manchin, a West Virginia Democrat who in the past has received a top “A” rating from the NRA, is now criticizing the group’s decision to grade lawmakers based in part on their votes on the background check measure, which failed to meet a 60-vote threshold Wednesday along with all other major gun-control proposals. Speaking Thursday at an event hosted by The Wall Street Journal, Manchin said his bipartisan compromise amendment, crafted with Republican Senator Pat Toomey, would have passed easily without the NRA’s decision.

Sen. Joe Manchin: “You know, if you’re going to score something, score the first one. The first one had Chuck Schumer’s bill, which I couldn’t vote for, OK? If you’re a gun-loving, Second Amendment defender, that’s the one you couldn’t even stomach. But I knew I had to get on that bill in order to change it. If they were true to their — you know, they said that we’ll score that one, and then this one makes sense, we won’t score this one.”

Gerald Seib: “What would have happened if they hadn’t scored it?”

Sen. Joe Manchin: “If they hadn’t scored it, it would have gotten 70 votes.”

An analysis by The Guardian and the Sunlight Foundation found all but three of 45 senators who torpedoed gun-control measures in the Senate this week have received money from firearms industry lobbyists. According to The Guardian, the NRA saw a spike in donations after the December shooting in Newtown, Connecticut, registering $2.7 million during January and February.