In numerous books that he wrote after his fall from the presidency, Richard M. Nixon clearly declared himself "pro-choice" on abortion, the same view later adopted by conservative Republican Senators Barry M. Goldwater and John G. Tower. It was said that in 1972, when abortion was not an issue, that McGovern was more "anti-abortion" than was RN. Abortion was not an issue until after Jan. 22, 1973, when the Right-to-Life Committee was formed.
I don't know what Nixon wrote after he was no longer president, but it doesn't take a lot of toodling around on the net to find ample evidence that Nixon's public stance prior to the 1972 election was anti-abortion. The pro-abortion folks certainly saw him as an enemy of their cause, and McGovern as at least a fellow-traveller.
It may be that Nixon was callously using it as a wedge issue, as he did with race and crime, and that he actually harbored other thoughts deep in his heart. But when it mattered (and back when Nixon mattered) -- back when it was naively thought that this was a purely state-by-state political and legislative issue -- Nixon's stance was anti-abortion. Consider his letter to Cardinal Cooke, supporting the Catholic Church's efforts to roll back New York's liberal abortion laws, a letter which evoked not a little ire.
McGovern did indeed make public statements that abortion should be a matter left to the states, because he feared that federal legislation might restrict the liberal abortion laws in his favorite states. But that was before Democrats discovered just how far they could get with the courts.
Abortion was most certainly an issue prior to 1973, as witnessed by the fights over changing state laws. If it were not a hot political issue, the libs wouldn't have felt the need to bypass state legislators and take the issue to the courts. They would rather just have pushed their non-controversial agenda through the legislatures of the 50 states.
Don't get me wrong, I don't view Nixon as some sort of knight on a white horse. I do know, having lived through that time, that Nixon's public stances on any number of issues of public morality made him beloved of decent people everywhere -- especially when the specter of McGovern was raised...
I realize that the NRLC feels that Nixon didn't do enough in the aftermath of Roe v. Wade. I would imagine that the answer is found in Chief Justice Burger's naive concurring opinion that stated that he didn't think that Roe v. Wade would have the sweeping effect that its dissenters said it would. Rehnquist and White were of course vindicated, but perhaps Nixon could be excused for not realizing who would be right on how things would turn out in practice. Reagan got taken to the cleaners on this issue when he was Governor as well.
The lines are a lot clearer in retrospect than they were then, especially since it wasn't an issue talked about over breakfast tables all that much...