The gun-control group founded by former New York mayor Michael R. Bloomberg (I) will begin surveying all federal candidates in the 2014 midterm elections on gun issues Monday as it tries to become a political counterweight to the National Rifle Association.

This is the first big step by Bloomberg — who has committed to spending $50 million of his personal fortune this year to build a national grass-roots movement that will pressure lawmakers to pass more restrictive gun laws — to devise a political strategy heading into the November elections.

Bloomberg’s group, Everytown for Gun Safety, is asking all Senate and House incumbents and candidates to complete a 10-part questionnaire stating publicly where they stand on issues such as expanding background checks for gun buyers, limiting the capacity of ammunition magazines and toughening gun-trafficking statutes.

The survey intends to make candidates state their positions on the record for the first time. Everytown plans to use their answers — as well as an analysis of any past legislative votes and public statements — to rally voters for or against them in key Senate and House races this fall, similar to how the NRA uses its ratings system to motivate pro-gun-rights voters.

“People deserve in this country to know where candidates stand on reasonable gun measures,” said John Feinblatt, the president of Everytown and Bloomberg’s longtime senior policy adviser. “For too long, the gun lobbyists had the field to themselves.”

Feinblatt and other strategists briefed The Washington Post on their plans ahead of Monday’s announcement.

Feinblatt said the group is focused on the 2014 midterms but plans to be active in elections for many years to come. “You don’t build a counterweight to the gun lobby overnight,” he said. “We’re in this for the long haul.”

Bloomberg has promised to spend more than double the roughly $20 million the NRA spends annually on political campaigns. Still, NRA spokesman Andrew Arulanandam said it will be difficult for Everytown to counter the political network and clout that the NRA, with its 5 million dues-paying members, has built up over decades.

“Money cannot buy the hearts and minds of the American people when it comes to the Second Amendment,” Arulanandam said. “Michael Bloomberg is just the latest incarnation of a long line of anti-freedom billionaires who’ve tried to take on the National Rifle Association.”

In 2013, Bloomberg emerged as perhaps the most prominent gun-control advocate during the Senate debate to expand background-check laws in the wake of the school shootings in Newtown, Conn. But despite the ad campaigns and lobbying efforts of Mayors Against Illegal Guns, the group Bloomberg funded, the Senate rejected a background-check compromise bill. Now, the issue is dormant on Capitol Hill.

Bloomberg has since started the new group, Everytown, merging the mayors coalition and Moms Demand Action for Gun Sense in America. Everytown’s goal is to create a grass-roots movement to pressure not only Congress but also state legislatures. It is using data-driven organizing techniques from Barack Obama’s 2008 and 2012 campaigns to expand its network of supporters, which now totals nearly 2 million.

“We’re going to be very, very data-driven, metrics-driven, making sure that we identify the people who care about this issue,” said Mitch Stewart, formerly the Obama campaign’s battleground-states director and now a political consultant advising Everytown.

Bloomberg initially wanted to award lawmakers grades of A through F, much like the NRA’s scorecards, but he has shifted the strategy in favor of a public questionnaire on key issues to motivate voters.

The NRA is one of Washington’s most powerful lobbying forces, but Feinblatt and Stewart pointed to recent elections as signs of its weakness. In 2012, NRA-backed candidates lost in six of the top seven Senate races the group targeted. And in 2013, Democrats defeated NRA-backed candidates in the top three statewide races in Virginia, where the gun-rights group is based.

“The NRA, they have this aura of being invincible,” Stewart said. “We’re going to show these candidates and these members of Congress that there is a sizable group of people in their districts and states who care about these issues and they’re going to demand some answers.”