There are two primary things that right wing bloggers and journalists have been pointing to with the regards to the vast left wing conspiracy against gun ownership: the Small Arms Treaty with the UN and the Fast and Furious operation of the Obama administration.
The UN Small Arms Treaty
About the Small Arms Treaty with the UN, there are articles such as this one where contributor Larry Bell writes, “While the terms have yet to be made public, if passed by the U.N. and ratified by our Senate, it will almost certainly force the U.S. To: [list follows].”
If you note that he uses the words “almost certainly” that means that he's making things up. There's been a whole lot of speculation on a bill that hasn't even been drafted yet. That article came from 2011, and the UN is set to meet July 2-29, 2012 to draft it.
Articles here, here, and here explain quite thoroughly that international treaties such as this one could impact international trade and then only if the US agrees to it. There would be no impact on domestic US gun ownership and trade. Any laws influencing that would have to be passed by Congress or the states.
In regards to those claiming a UN treaty constitutes an attack on the US 2nd Amendment, David Fidler, international law professor at Indiana University, says, “They show next to no understanding of how international law works in the context of the United States Constitution.”
The Fast and Furious
Some bloggers and journalists claim that an ATF operation gave guns (i.e. walked the guns) to Mexican cartels so that the ensuing gun violence on Americans would cause an outcry allowing the US government to restrict gun ownership in the US.
An article in Fortune clearly described the operation. Starting in 2009, an ATF operation was tasked to monitor suspected gun smugglers who funnel American guns to Mexico. An estimated 2,000 guns are smuggled out of the US to Mexico per day. In Arizona, there is no waiting period and individuals can buy an unlimited number of guns per purchase. They had a list of 31 suspects by June 2010; however, the US Attorney's office would not indict any suspects. These suspects were Americans without criminal records whom were allegedly paid by Mexican criminals to purchase guns. In December 2010, a US Border Patrol Agent was killed by a gun purchased by a suspect flagged by the Fast and Furious operation.
A disgruntled ATF agent who allegedly had wanted to take matters into his own hands began complaining about his superiors in the ATF operation (who'd had their hands tied by the US Attorney's office) and a Congressional investigation was launched. It's apparent from knowing the details of the actual operation that no guns were deliberately walked into the hands of criminals and that it was in fact prosecutors who wouldn't permit the arrest of Americans suspected of handing over guns to Mexican nationals. It is, in fact, very surprising that members of Congress, backed by the NRA, would be acting based on conspiracy theories. It's even more surprising that, in essence, the NRA would be upset that the ATF didn't arrest US gun purchasers in a more timely fashion to possibly prevent a border patrol agent's death. It's as if they're suggesting that guns, not people, kill people.
It appears that the only guns that the ATF may have been involved in losing were the result of the formerly mentioned disgruntled ATF agent. Said agent, John Dodson, had posed as a smuggler in a one-off operation which his immediate supervisor had refused to approve. Dodson then took vacation before the guns were recovered, and they were never recovered. The ATF had a clear policy of not intentionally losing (or walking) guns. Yet, one hot-headed agent lost some. This hardly constitutes a government conspiracy to deliberately arm criminals in attempt to increase gun violence and restrict the 2nd Amendment.
The operation's predecessor, the Bush administration's Operation Wide Receiver, was a gun walking operation which used faulty tracking methods.
What Have Democrats Actually Done?
Historically, Democrats have not been as much in the pocket of the NRA as Republicans and have been more for gun regulation (some more than others). However, this is a fight they have largely abandoned or merely chosen not to fight.
As President, the only gun-related legislation Obama has backed or signed was to make gun ownership and purchasing more permissive (reversing Bush laws that prevented people from bringing guns onto Amtrak trains and into national parks); however, before he became President, he supported and voted for laws to regulate guns. He's said that he supports the 2nd Amendment but wants reasonable regulation to make the country safer. It's been said that if existing laws were enforced, the man who shot Congresswoman Gabrielle Giffords and killed others wouldn't have been able to buy a gun.
From this, it's clear that there's no evidence of a vast anti-gun left wing conspiracy. Hopefully, reasonable people can discuss whether supporting the 2nd Amendment means that all places should be like Arizona where there's no waiting period, unlimited gun purchases can be made by individuals, and individuals can resell guns with no background check. Arizona also appears to be the gun smuggling capital of the US. Does it also mean that every individual should be able to own weapons that give individuals the power of small army units which the Founders likely didn't imagine: such as assault weapons, rocket launchers, and flamethrowers?