The group that Bloomberg co-chairs, Mayors Against Illegal Guns, will run ads in 13 states during the Easter and Passover recess focused on expanding background checks for gun purchases. The group identified a mix of 15 vulnerable Democrats, swing-state lawmakers and solidly supported Republicans in states where, the group said, “they can most influence the upcoming Senate vote.”

They include Sens. Jeff Flake (R- Ariz.), Mark Pryor (D-Ark.), Saxby Chambliss (R-Ga.), Johnny Isakson (R-Ga.), Joe Donnelly (D-Ind.), Dan Coats (R-Ind.), Chuck Grassley (R-Iowa), Mary Landrieu (D-La.), Susan Collins (R-Maine), Kelly Ayotte (R-N.H.), Dean Heller (R-Nev.), Kay Hagan (D-N.C.), Heidi Heitkamp (D-N.D.), Rob Portman (R-Ohio) and Pat Toomey (R-Pa.).

”We demanded a plan and we got one,” Bloomberg saidon Twitter. “We demanded a vote and we’ll get one. Now we’re doing all we can to pass a bill that will save lives.”

The New York Times first reportednews of the ad buy.

Senate Majority Leader Harry Reid (D-Nev.) plansto schedule a vote on a gun-control package in early April, and he has said he wants the legislation to include stricter background checks. Sen. Joe Manchin (D-W.Va.) is privately talkingwith the National Rifle Association — of which he is a member — about the position the group may take on an expanded background-checks measure.

The Bloomberg group’s announcement did not discuss an assault weapons ban. The proposals expected on the Senate floor next month will not include an assault weapons ban, but Reid has said he will allow amendments proposing one.

The NRA reportedly will address lawmakers in an ad campaign running simultaneously with Bloomberg’s. An NRA lobbyist told the newspaper that the NRA campaign could not match Bloomberg’s “dollar for dollar.”

Bloomberg and NRA CEO Wayne LaPierre are setto appear on NBC’s “Meet the Press” on Sunday.