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The National Rifle Association's annual convention in Indianapolis kicked off Friday and its leaders immediately came out swinging against Michael Bloomberg and his new gun control push with the group's top lobbyist calling the former New York City mayor an "arrogant hypocrite."

"Stay out of our homes, stay out of our refrigerators, and stay the hell out of our gun cabinets because this freedom is not for sale," Cox said to cheers from those gathered. Some 70,000 NRA members were expected to attend from all over the country.

He also noted Bloomberg's interview with the New York Times last week where he said "if there is a God, when I get to heaven I'm not stopping to be interviewed. I am heading straight in. I have earned my place in heaven. It's not even close."

I've looked, but I can't find anywhere in the scripture that says the way to get into heaven is deny good people the right to defend themselves from criminal attack. I believe God gave us this freedom," Cox said.

NRA executive vice president Wayne LaPierre promised the NRA "will not back down-not now, not ever" and said gun rights supporters should keep November's midterm elections in their sights, saying it will be a "bare knuckled street fight."

"Freedom has never needed our defense more than now," LaPierre said. "So I ask you this afternoon - do you trust this government really to protect you and your family? We're on our own. That's a certainty."

He promised the NRA will "not go quietly into the night. We will fight all over the heartland of this country, from one ocean to the other."

"Our opponents are shrewd," he said. "And you know it as well as I do, they are skilled in spinning webs of deceit. Their coffers, they're full, believe me. And their sights are set clearly on this fall's election…They're going after every house seat, every senate seat, every governor's chair, every state house, that they can get their hands on. And they're out there laying the ground work to put a Clinton back in the White House. They intend to finish the job, make no mistake about it. To fulfill their commitment, their dream of fundamentally transforming America, an America that when they're through, you won't recognize."

Bloomberg launched his new group, Everytown for Gun Safety, last week and said he would put $50 million of his own money behind it to build an effort to take on the NRA. Activists from the group, as well as victims of gun violence from all over the country including ones from Newtown, Conn., and Aurora, Colo., traveled to Indianapolis for the convention. The group also said over 100 moms that are part of the group would be in attendance.

LaPierre mentioned Bloomberg and his millions and then gave his team's response: a video of Americans promising to each pledge $25 to fight Bloomberg.

"It's people," LaPierre said, referring to the video. "It's Americans in their hearts. And this election is going to be won or lost on every street, on every corner, in every coffee shop, every store and every church in America where every NRA member lives and works and volunteers and campaigns. Those NRA members and those great Americans just like them all over this country - they are the real muscle of NRA's clout and together we will stand as members of the NRA and stand and fight to take back our country."

Possible 2016 contenders also spoke to the crowd including Louisiana Gov. Bobby Jindal, Sen. Marco Rubio of Florida, Indiana Gov. Mike Pence, and former senator and presidential candidate Rick Santorum.

Republican Senate Leader Mitch McConnell, who's facing a tough re-election battle of his own in Kentucky this year, spoke at the conference as well. He did not carry out a long rifle, as he did when addressing activists at this year's Conservative Action Political Conference in March.

Sen. Ted Cruz of Texas and Gov. Scott Walker of Wisconsin, also possible 2016 candidates, addressed the group via video. Cruz thanked attendees for fighting gun control efforts and said the "Second Amendment is under constant siege by Democrats in Washington" who are eager to take advantage of "any tragedy."

Rubio didn't mention Bloomberg directly, but said NRA members need to fight those in "entertainment and media" who perpetuate "stereotypical myths" against gun owners, adding "many of these leading voices who want to take away your right to protect your families, they themselves are well protected with the kinds of guns they do not want you to have."

"Take comfort because in just 32 months we will have a new president. And our current president should take comfort because in 32 months he can return home to live in the anti-gun utopia that is Chicago," he said.

He also told a story about a young female staffer in his office and what she had to go through to legally carry a weapon in Washington, D.C., after moving from Florida where it was already registered.

"What criminal would ever subject themselves to this process?" he asked.

The NRA is pushing for federal legislation that would allow concealed carry permits in one state to apply when gun owners travel to another state. It's something they are highlighting during this conference. Sen. John Cornyn of Texas introduced legislation earlier this year and Rubio was one of its co-sponsors.

In his speech Rubio said gun owners "wept and mourned just like the rest of this country" after mass shootings, but they shouldn't affect gun rights.

After the massacre at the Sandy Hook Elementary School in Newtown, gun control advocates proposed legislation for universal background checks and a ban on semi-automatic weapons and high-capacity ammunition magazines, but it failed to pass Congress.

Jindal closed out the first day warning those gathered the fight they are waging will "rage on long after the coming election, long after the next election…they are not going to be satisfied until they have fundamentally altered the ideological foundation of this country."

Jindal said "we cannot let them win" and then said Bloomberg, as well as Attorney General Eric Holder, want to take away Americans' freedoms.

"Let's be honest they think government should pick your soft drink, your snack food, you vices, your home security system, your health insurance, your electricity use, and your children's school as well," Jindal said. "They think we are too dumb to order pizza, too dumb to protect our land. They take perhaps the most pessimistic view of Americans we have ever seen from national leaders in our history. If you listen to them you get the idea we can't tie our own shoelaces without government intervention. "

Jindal said the "problem" is not just Bloomberg or Holder or it would be "solve(d)" with " just a few elections," but the "truth is Michael Bloomberg, Eric Holder, so many of Barack Obama's wealthiest liberal backers in Hollywood in fact do not believe in the Second Amendment at all. ..they think the Second Amendment is a phrase from a speechwriter. "

The convention continues through the weekend with speakers including Sarah Palin expected to take the stage.

ABC's Ryan Struyk contributed to this report.