Just three years ago, Manchin was proud to have the NRA's support. Now he's going after them.

Sen. Joe Manchin, co-author of a plan to expand background checks on gun sales, is launching a TV ad to defend himself from attacks by the powerful National Rifle Association. [...] The NRA is spending at least $100,000 on its ad campaign hitting Manchin, and an aide for the senator says he plans to “at least match” that buy. [...] Manchin has been increasingly critical of top NRA officials in recent months, attempting to portray the organization’s leaders as out-of-step with its 5 million rank-and-file members. He accused the NRA of lying about the background checks measure during the Senate debate. “They are telling members that our legislation would criminalize the private transfer of firearms by honest, law abiding citizens,” he said in April. “That is a lie, that is simply a lie and anyone that can read knows that is not factual.” “The Washington NRA leadership is clearly out of step with the American people and law abiding gun owners, and is now attacking Senator Manchin for a position they once supported,” said Manchin aide Jonathan Kott. “The Washington NRA leadership is trying to distort Senator Manchin’s commitment to the [Second] Amendment because they know he is one of the most credible defenders of gun rights who also believes that it just makes sense to keep guns out of the hands of criminals and those found severely mentally ill.”

Sen. Joe Manchin isn't up for reelection until 2018, but he's not taking the National Rifle Association's decision to attack him lightly. In fact, he seems to see it as an opportunity This a perfect illustration of how the NRA has become a fringe group. Manchin is the kind of Democrat that the NRA depended on to claim its place as a political heavyweight. Sure, it leaned to the right, but there were still Democrats like Manchin who wanted to the NRA's support and were proud to receive it. But now that's changed, and it's not because Manchin has moved to the left—it's because the NRA can't accept even the most modest of gun safety measures.

On a political level, this is a battle that Manchin is going to win. And in the process, he's going to put to rest the myth that Democrats in conservative states need the NRA on their side, because in fact it's the exactly the other way around.