Gov. Bruce Rauner said Tuesday he and his aides were “working feverishly” to study the gun dealer licensing bill before he decided to veto it because “it was going to create a big layer of burden and bureaucracy, and really not keep our communities safer.”

“And so we decided let’s go ahead and veto the bill,” he said.

Speaking after a campaign stop in Naperville, the governor insisted his decision had nothing to do with trying to shore up conservative support a week before the primary.

“Not at all,” Rauner told the Chicago Sun-Times. “What we are focused on is winning in November against Pritzker and Madigan, and our message is a unifying message. It’s the right policy that everybody wants.”

“It just took time to study it to determine the right answer was to veto that one.”

“The right thing is to do a package, and I’m still going to push a package. I’m tired of waiting. The General Assembly still hasn’t passed what I think is really going to make sense. That was the only bill that got to my desk. It really wasn’t going to improve anything. It was just going to create a bureaucracy that would be harmful.”

Rauner’s veto came after Democratic pressure from Mayor Rahm Emanuel, House Speaker Mike Madigan and J.B. Pritzker and other gubernatorial rivals just days before the primary election.

“Our team has been working feverishly, studying, talking, doing our due diligence on what other states have done, what’s the law here, and what it would do to our small shop owners,” the governor said after meeting with voters at Hugo’s Frog Bar in Naperville. “And we just decided it was going to create a big layer of burden and bureaucracy, and really not keep our communities safer. And so we decided let’s go ahead and veto the bill.”

In his official veto message, Rauner said: “The core issue is not which guns to legally ban or regulate.”

“We have ample proof that such narrowly focused legislative responses make for good political cover, but they do little to stop the illegal flow of guns into Illinois or prevent people from committing thousands of crimes in our state each year with illegal guns.”

RELATED: Chicago Sun-Times 2018 Illinois Primary Voting Guide

One of the bill’s chief sponsors, State Sen. Don Harmon, D-Oak Park, on Tuesday accused Rauner of being a “lap dog” for the National Rifle Association “rather than listen to the people he represents.”

“Eighty-five percent of Illinoisans support licensing gun dealers,” Harmon said in a statement. “Governor Rauner has decided to be the governor of the nine percent who don’t.”

But the NRA in turn said the bill created “dramatic overreaches specifically designed to close as many Illinois federally licensed firearm dealers as possible.”

“Now it’s up to the law-abiding gun owners of Illinois to let their lawmakers know this type of infringement on their Second Amendment Rights is completely unacceptable,” NRA spokesman Lars Dalseide said in a statement. “Punishing legitimate businesses for the criminal actions of others is a prime example of why communities continue to suffer as their elected officials focus on headlines instead of the real problem; actual criminals.”

And the Illinois State Rifle Association called it a “bad bill,” while applauding Rauner’s decision.

“The intent of the bill was not what they said. The intent of the bill is to force small firearm dealers out of business,” spokesman Richard Pearson said. “It just becomes so expensive that you can’t do it…It’s just an attack on firearm dealers rights and that’s all it is.”

Rauner had signaled his intentions earlier in the day during an interview with WJPF, a radio station in southern Illinois, while also revealing he is a member of the NRA.

“I have been [an NRA member] for many years I’m a hunter. I’m a gun owner. I’m a Second Amendment supporter,” Rauner said.

The governor, in saying he would veto the bill, called on the four legislative leaders to appoint members to a public safety commission to talk about mental health and school safety, according to the governor’s office.

Asked what he’d do about the bill on Monday, Rauner repeatedly said he favored a “comprehensive solution,” without answering what he’d do with it.

The measure, which brought out everyone from Cardinal Blase Cupich to Chicago Police Supt. Eddie Johnson to advocate for it in Springfield, would have required gun dealers to be licensed by the Illinois Department of Financial and Professional Regulation, and not just the Bureau of Alcohol, Tobacco Firearms and Explosives. The cost would have been limited to $1,000 every five years.

The measure would have also required dealers and employees to be trained to conduct background checks, stop thefts, store guns and prevent straw purchasing — which is at the heart of why Chicago’s top officials kept hammering the Republican governor to sign it.

A “Gun Trace Report” released last year by Chicago Police found straw purchases continue to be a major factor in guns going from the open market to the secondary market, oftentimes stymying police efforts to trace the weapons’ origins. In instances where someone was arrested and a gun was recovered, the report found the overwhelming majority of guns were not bought by the person arrested.

Straw purchasers will also sometimes lie to police and say their gun was lost or stolen “as an excuse intended to cut off further investigation,” according to the report. To stem the tide of shootings, the report actually recommending to pass the gun dealer licensing bill to help curb straw purchasing, impose anti-theft measures and help police in their gun trafficking investigations.

Rauner has traditionally steered the gun control conversation to dealing with “mental illness.” And he’s also avoided answering specifics about whether he supports an assault weapons ban.

In recent days, he’s advocated for a ban on bump stocks. Last week he said he supports “common sense bipartisan reform,” while vouching support for keeping guns “out of the hands of criminals and the mentally ill, first and foremost.”

“I believe we should also come together to find out ways to increase school safety, increase the safety of our students and our teachers in our schools, and the other thing I think we can all agree on is we got to do a better job supporting our police officers, our law enforcement, who put their safety at risk to keep us safer,” Rauner said last week.

The gun dealer licensing bill was sent to the governor’s desk on Feb. 28, and he had 60 days to decide whether to sign the bill, veto it or do nothing and let it take effect.

Since then, Emanuel and Johnson repeatedly publicly pressured the governor to sign it. Emanuel and Johnson on Monday held a news conference flanked by the parents of children who have been killed on Chicago streets.

Other gun control bills yet to reach Rauner’s desk would raise the minimum age from 18 to 21 to buy an assault rifle, and ban the sale of bump stocks and other modifications and require a 72-hour “cooling off” period on purchasing assault rifle sales. And another, named after recently-slain Chicago Police Cmdr. Paul Bauer, would ban the sale of body armor and high-capacity gun magazines to anyone other than police officers, licensed security guards and members of the armed forces.

At a news conference at police headquarters, Emanuel charged that Rauner had “abdicated his leadership” and let Republican primary politics trump a governor’s “primary responsibility” to provide public safety.

“I’ve been in public life for 30 years. I know politics when I see it. This is about his primary election and not his primary responsibility as governor,” the mayor said.

“It was not cramming for his final exam when he was studying the legislation. He was getting a little political heat in the primary and he decided to end that heat. He doesn’t know what the heat of the general election is gonna look like.”

He added: “This has everything to do with politics and nothing to do with public safety and there are consequences to that decision because, after Florida, we’re at an inflection point we have not seen in a long time.”

Emanuel said what’s “even worse” is that Rauner “pulled the rug out from under” students who will walk out of their classrooms on Wednesday in solidarity with students in Parkland, Fla. where 17 young people and staffers were gunned down by a 19-year-old orphan once expelled from Marjory Stoneman Douglas High School.

The mayor urged those same students to turn their “activism into action” and “vote the vote” by making Rauner pay at the polls.

“Use that veto for your own political awareness and activism to then say there are consequences to voting and having people in elected office who share our ideals.”

Johnson said he had been heartened when the gun dealer licensing bill landed on the governor’s desk just weeks after 18th District Police Commander Paul Bauer was gunned down in broad daylight outside the Thompson Center.

“Today, we’re saying politics taking priority over doing the right thing,” Johnson said. “With the governor’s veto, it will be that much more difficult for law enforcement throughout the state to stem the flow or illegal guns into our neighborhoods.”

Contributing: Fran Spielman