Although latest gun bill was by Senators Pat Toomey (R-PA) and Joe Manchin (D-WV), it is actually the Toomey-Schumer-Manchin bill. According to the Wall Street Journal, Senator Chuck Schumer (D-NY) "helped negotiate the final bill."
Even more interesting is this Roll Call report:
...Toomey's public support for the bill hinged on not having to stand next to Democratic Sen. Charles E. Schumer of New York" at the press conference.
"Manchin and Toomey are the best people to sell this agreement to the pro-gun community, and Schumer doesn't want to get in the way of that. His job is to persuade the gun safety groups that it's an acceptable deal," a Democratic aide said of the group's dynamic.
Heritage Action CEO Michael Needham said the following about the backroom dance:
Americans are tired of backroom deals. Legislation drafted behind closed doors and rushed to the Senate floor has no place in our political system. We expect this type of deal making from Joe Manchin and also from Chuck Schumer, who supports the "universal registration" of firearms. However, we expect more from Pat Toomey and, more importantly, so do his constituents.
To be clear, lawmakers will not get a pass on any bill that infringes on the constitutional rights of the American people. As Lady Thatcher said, "If you just set out to be liked, you will be prepared to compromise on anything at anytime, and would achieve nothing."