Updated at 5:10 EST with audio of the call.  —  Updated at 6:12pm EST with confirmation that the call did indeed come from the Santorum campaign  —  LANSING, MI — Rick Santorum's campaign is locked in a tight battle with Mitt Romney ahead of Tuesday's Michigan primary.

Momentum back toward Santorum in MI?  —  PPP's final poll in Michigan finds Rick Santorum holding on to the smallest of leads with 38% to 37% for Mitt Romney, 14% for Ron Paul, and 9% for Newt Gingrich.  —  It's always good to be cautious with one night poll numbers, but momentum seems to be swinging in Santorum's direction.

Romney also said he voted in Dem primaries to influence the race  —  The Romney campaign has been denouncing Democratic efforts - and now those by Rick Santorum - to get Democrats to vote in Michigan's open primary.  —  Mitt Romney himself called it a “new low” in politics in a round of TV interviews.

Climate Change, Part I: Catastrophe  —  Tomorrow and the day after, a panel of the U.S. Court of Appeals for the D.C. Circuit (Judges Rogers, Sentelle, and Tatel) will hear oral arguments in a raft of cases challenging the Environmental Protection Agency's rules on the regulation of carbon dioxide (CO2) and other greenhouse gases (GHG).