Sen. Joe ManchinJoseph (Joe) ManchinOvernight Finance: House sends Dodd-Frank rollbacks to Trump | What's in the bill | Trump says there is 'no deal' to help ZTE | Panel approves bill to toughen foreign investment reviews House votes to ease regulation of banks, sending bill to Trump Senators demand answers on Trump’s ZTE deal MORE (D-W.Va.) on Thursday hit back at the National Rifle Association, accusing its leaders of shifting their stance on background checks for political gain and unveiling a new television ad defending his bipartisan gun control measure.

"They're trying to say Joe Manchin's changed — I haven't changed, I'm the same Joe Manchin I've always been, and people back home know me," the West Virginia lawmaker told MSNBC. "The bottom line is the leadership of the NRA in Washington has changed."

Manchin, along with Sen. Pat Toomey (R-Pa.), co-authored a Senate bill that would have expanded background checks to include firearm purchases at gun shows and over the Internet. That legislation, which came up five votes short in the Senate, earned the ire of the NRA. The group has subsequently gone up with an attack ad hitting Manchin in his home state.

Despite not facing reelection until 2018, Manchin announced he would defend himself with an ad of his own, which he debuted for the first time on "Morning Joe."

In the ad, Manchin tells West Virginians that "you know I've always fought for our gun rights," and urges them to call the NRA and voice support for his bill.

Manchin said he was happy to engage with the powerful gun lobby over the legislation, especially if that meant the bill passing Congress and perhaps saving lives.

"Why do we ask to be policymakers and be involved in the public progress when we're afraid basically to engage? ... I'm not afraid to engage," Manchin said.

"The worst they can do is send me back to my family and the state that I love."