A true game-changing VP candidate swings the race in November. One example is Lyndon Johnson, who in 1960 carried the day for John F. Kennedy by delivering southern states. This is recounted very absorbingly in Robert Caro’s recent book, which I highly recommend.

The post-Ryan swing is now close to 4 points of Meta-margin in size, and appears to have brought the race to a momentary near-tie. Democrats might be pondering ways to bring the subject back to Romney. More swings lie ahead.

I should point out that the gray zone above is the nominal 95% CI, and includes pollster biases. Because these tend to cancel out, the true CI is smaller.

I do not see a reason yet to change the long-term prediction. President Obama’s average lead to date suggests that re-election is still very likely. I’ll elaborate later with more evidence.

In the meantime, here is an excellent article on President Johnson’s private views, as revealed through taped Oval Office conversations. He used the aftermath of the Kennedy assassination, and his unexpected elevation to the Presidency, to further those views and to shape U.S. society in ways that are at the core of this year’s election debate: Medicare and the Voting Rights Act.