I am not a nuclear energy proponent... the only nuclear legislation that I've passed has been to make sure that the nuclear industry has to disclose [radioactive leaks] and share that with local and state communities. I just did that last year.
But the NY Times claims that (i) the legislation was eventually watered down to merely encourage rather than require public disclosure; and (ii) it didn't pass anyway.
Asked why Mr. Obama had cited it as an accomplishment while campaigning for president, the campaign noted that after the senator introduced his bill, nuclear plants started making such reports on a voluntary basis. The campaign did not directly address the question of why Mr. Obama had told Iowa voters that the legislation had passed.
Obama's website disputes the first claim, at least:
NYT never mentions that the revised bill, like the original, required notification of public leaks and that the only change was that requirements would be made through the regulatory process.
Piecing things together, the best I can work out is that the original bill mandated disclosure of even small leaks - any exceeding “allowable limits for normal operation”, whereas the revised bill only mandated disclosure of leaks "exceeding the levels set by the Nuclear Regulatory Commission and the EPA". The NRC would have up to 2 years to decide these limits, and even after that it would remain merely voluntary to disclose smaller leaks. The following section from the NYT article is also relevant:
[Some] say that turning the whole matter over to the Nuclear Regulatory Commission, as Mr. Obama’s revised bill would have done, played into the hands of the nuclear power industry, which they say has little to fear from the regulators. Mr. Obama seemed to share those concerns when he told a New Hampshire newspaper last year that the commission “is a moribund agency that needs to be revamped and has become a captive of the industry it regulates.”
Conclusions: (i) It's technically true that even the revised bill would mandate disclosure of some leaks. But it's misleading spin for the Obama "fact-checkers" to deny the Times' claims that the revised bill was watered down. They would do better to acknowledge the fact that legislative compromise is sometimes necessary in politics. That's nothing to be ashamed of -- unlike, say, misleading your supporters.
(ii) Nobody disputes that Obama asserted a simple falsehood when he said the legislation "passed". It didn't. But given that this is a one-off mistake made in conversation (in contrast to the Clintons' lies), I'm inclined to give him the benefit of the doubt. He probably just misspoke: you can see from the context that he was trying to convey his cautious stance on nuclear issues, and this point would have been made just as well had he said "the only nuclear legislation that I've supported", or "introduced", or something along those lines.
N.B. I'd like to get to the bottom of this (if I haven't already), so please correct me if you find any evidence that the above analysis is mistaken.