New York City Mayor Michael Bloomberg's (I) gun-control group is taking a page straight from the NRA's playbook, announcing on Tuesday a grading system that will rank lawmakers based on their positions on gun laws.

As the Washington Post first reported, Mayors Against Illegal Guns, the nonprofit Bloomberg founded and now co-chairs, will assign letter grades from A through F to politicians as a way of assessing their stance on gun measures in a way that the public can easily grasp. The NRA has used that exact tactic for years, but in reverse, with politicians receiving better grades the more they adhere to the gun-rights line. 

"For decades, the NRA has done an admirable job of tracking to minute detail how members of Congress stand on gun bills," Mark Glaze, director of Mayors Against Illegal Guns, told the Post. "We've simply decided to do the same." 

According to Glaze, the ratings will use an algorithm to crunch not only lawmakers' votes on key bills, but their statements and actions as well. The group hopes its scorecards, like the NRA's, will serve as a handy guide for voters and donors who are otherwise unsure which candidates to back.  

"We're asked many times daily where people's elected representatives are on gun laws, and we intend to tell them, in detail," Glaze told CNN on Tuesday. 

As Reid Cherlin wrote for GQ last year, the NRA has effectively used their letter grades to rally support or opposition to pending legislation, particularly among members of the lower chamber. 

"In part because House members have to run for re-election every two years, the NRA grades have become a vital part of how candidates portray themselves to voters — and conservative and swing-district members will do everything they can to keep a good rating," Cherlin said. 

By issuing its own rankings, Mayors Against Illegal Guns hopes to provide a counterweight that will make it easier for on-the-fence legislators to side with the gun-control crowd. In addition, they believe the rankings will help steer funding to gun-control advocates and, with that reward in sight, convince some vulnerable politicians in need of a fundraising bump to strive for good grades. 

Last month, two Democratic mega-donors threatened to withhold funding from any candidates who broke with the party on universal background checks for gun purchases. 

For now though, the NRA is scoffing at the notion that Bloomberg's grades will carry much weight. 

"The reason NRA scorecards are effective is that they have the weight of approximately 5 million dues-paying members and tens of millions of other supporters behind them," Andrew Arulanandam, an NRA spokesman told the Post. "We'll take that over the purse of one billionaire any day of the week and twice on Sunday."

The announcement comes on the heels of Bloomberg's nonprofit announcing a huge, $12 million ad campaign aimed at convincing lawmakers in 13 states to support gun legislation currently pending in Congress. Democrats in the Senate are hoping to bring that legislation to a vote sometime soon, though Republicans have threatened to filibuster it.