NEW YORK — New York City Mayor Michael Bloomberg, a staunch advocate of tougher gun control laws, will bankroll a $12 million national advertising campaign aimed at key members in the U.S. Senate, the mayor said in an interview with The New York Times published on Saturday.

The commercials to be run by Mayors Against Illegal Guns feature a hunter with a rifle, vowing to protect the right to bear arms and voicing support for comprehensive background checks “so criminals and the dangerously mentally ill can’t buy guns.”

The advertising campaign will run in 13 states to target specific members of the U.S. Senate during the upcoming Congressional recess, according to the organization, of which Bloomberg is a co-chairman.

Bloomberg, who leaves office in January after three terms as Mayor of New York, has championed gun control and been particularly outspoken since a gunman killed 20 students and six adults at a Newtown, Conn., elementary school in December.

Last week, he appeared at City Hall with parents of some of the Newtown victims and Vice President Joe Biden, who is spearheading the Obama administration’s efforts to curb gun violence.

The Times said Bloomberg, a self-made billionaire, would bankroll the ad campaign. A spokesman for the mayor could not be immediately reached to comment.

The ad campaign marks a push back against the National Rifle Association, the mayor said in the Times interview.

“The N.R.A. has just had this field to itself,” Bloomberg said. “It’s the only one that’s been speaking out. It’s time for another voice.”

The Senate is set to begin considering gun legislation when Congress returns from its Easter recess in the second week of April.

“These ads bring the voices of Americans — who overwhelmingly support comprehensive and enforceable background checks — into the discussion to move Senators to immediately take action to prevent gun violence,” said Bloomberg in a statement released by Mayors Against Illegal Guns.

Targeted in the campaign are Arizona and Republican Sen. Jeff Flake; Arkansas and Democrat Sen. Mark Pryor; Georgia and Republican Sens. Saxby Chambliss and Johnny Isakson; Indiana and Democratic Sen.Joe Donnelly and Republican Sen. Dan Coats; Iowa and Republican Sen. Chuck Grassley; Louisiana and Democratic Sen. Mary Landrieu; Maine and Republican Sen. Susan Collins; New Hampshire and Republican Sen. Kelly Ayotte; Nevada and Republican Sen. Dean Heller; North Carolina and Democratic Sen. Kay Hagan; North Dakota and Democratic Sen. Heidi Heitkamp; Ohio and Republican Sen. Rob Portman; and Pennsylvania and Republican Sen. Pat Toomey, the group said.