WASHINGTON (CNN) -

The group formed by former New York City Mayor Michael Bloomberg is trying to pressure political candidates to come out publicly in support of some gun control measures.

Everytown for Gun Safety on Monday released a questionnaire it's sending to candidates as it decides which ones to support in this year's midterm elections.

This questionnaire and the hiring of field staff in more than a dozen key states are the result of Bloomberg's pledge in April to spend $50 million this election year to help support candidates who will back further gun control efforts and to combat the politically powerful National Rifle Association.

Among the issues his group will ask candidates about include one of its priorities: closing the so-called gun show loophole where not everyone who buys a gun at a show must undergo a background check.

Other issues it asks about include tightening possession restrictions on domestic abusers, prosecuting gun traffickers and preventing access by children to guns, according to a copy of the questionnaire.

"Now it is time for political candidates to tell us where they stand," John Feinblatt, president of Everytown for Gun Safety, told reporters Monday on a conference call.

"For too long candidates only heard from the gun lobby."

As it decides whether to endorse candidates, the NRA gives them letter grades based on a private survey as well as their records. Group officials told CNN they believe history has shown loyalty is not just based on how much money is spent trying to build loyalty.

"The power of the NRA does not come from the questionnaires we send to people who are running," spokesman Andrew Arulanandam said.

"The power of the NRA comes from our 5 million plus dues paying members."

It is expected that by early fall the NRA will have made all of its mid-term endorsements.

As a political force, Everytown is trying to match the success seen by the NRA.

Everytown officials acknowledge gun control advocates need to do a better job of mobilizing their supporters and say this year's election will begin to show whether they can succeed.

This year will be the "first chance... not (the) last chance," senior adviser Mitch Stewart told reporters.

Stewart is a veteran of the Obama 2008 and 2012 campaigns. He said this effort will be data and metrics-driven, similar to what he oversaw in those campaigns. To help bolster its ranks of volunteers, help identify and communicate with voters who are supporters and to help mobilize their turnout at the polls, Everytown is hiring field staff in more than a dozen politically key states, including Arizona, Colorado, Minnesota, Montana, Nevada, New Hampshire, North Carolina, Ohio, Oregon, Pennsylvania, Texas and Virginia.

Group officials said the questionnaire is part one of their Gun Sense Voter Campaign, which is trying to mobilize one million Americans to vote in the midterms for those candidates who pledge to support gun safety measures. They say so far more than 650,000 have signed.

While polls have shown a majority of Americans support stricter background checks, the Senate last year failed to pass that as well as other measures despite the emotional fallout from the Newtown, Connecticut, school shooting and a strong push for the measures from the White House.