[Petronski]

Here's the intrade betting on "McCain wins the GOP Nomination" in the last sixty days.

Notice the peak around May 14.

What could have happened then?

By ROBERT PEAR and JIM RUTENBERG
Published: May 18, 2007

WASHINGTON, May 17 — Senate negotiators from both parties announced Thursday that they had reached agreement on a comprehensive immigration bill that would offer legal status to most of the nation’s 12 million illegal immigrants while also toughening border security.

[Kevmo]

gee, ya think they’re related?

Great post. Bump.

[bcsco]

By ROBERT PEAR and JIM RUTENBERG
Published: May 18, 2007

May 18th is the exact date the downward spiral began in earnest in your chart. Two bars to the right of the 16th is when it began, and free fell until the 23rd, with a somewhat less accelerated drop off since.