When Romney ran for governor, he never once said he was endorsed by the NRA. And in fact, he was not endorsed by the NRA.
When the issue came up recently, the campaign pointed out that Romney was not endorsed by the NRA in his run for Governor, which is why Romney used the word “support”, not “endorse”. The NRA did provide support to his campaign.
Just like Fred Thompson just sent me another nice e-mail saying I’ve supported him, and thanking me. I haven’t endorsed him, but we all know that “endorse” is a different word than “support”.
Maybe you are confused because the NRA endorsed his work on the AWB bill. They are two different things, and sometimes people get them mixed up.
Per the interview
Maybe it was the pressure of the moment. Being under the Tim Russert spotlight can get to anyone. Under Russert's grilling about guns on this morning's "Meet the Press," former Massachusetts governor Mitt Romney claimed an endorsement he'd never won.
In answer to questions about whether he would sign an assault weapons ban, Romney said: "Just as the president said, he would have, he would have signed that bill if it came to his desk, and so would have I. And, and, and yet I also was pleased to have the support of the NRA when I ran for governor. I sought it, I seek it now. I'd love to have their support."
Later in the interview, he added the following:
"I just talked about, about guns. I told you what my position was, and what I, what I did as governor; the fact that I received the endorsement of the NRA."
Straight from slick master himself!
http://blog.washingtonpost.com/the-trail/2007/12/16/romney_claims_nra_endorsement.html