The New Republic is out with its story about the internal deliberations at the Times over the McCain story.

By some accounts, the fact that TNR was prepping this story is what prompted the Times to publish when it did, although the truth is somewhat more complicated than that, it appears.

However, if you were looking for a complete answer to the question, Why publish now?, TNR doesn't have it either. For instance:

In late December, according to Times sources, Keller told the reporters and the story's editor, Rebecca Corbett, that he was holding the piece in part because they could not secure documentary proof of the alleged affair beyond anecdotal evidence. Keller felt that given the on-the-record-denials by McCain and Iseman, the reporters needed more than the circumstantial evidence they had assembled to prove the case.

The story the Times published has no documentary evidence of the affair. The only circumstantial evidence that jumps out to me is that some aides were "[c]onvinced the relationship had become romantic."

So what changed?