"Recent Senate retirements in Arizona and New Mexico and competitive races in Nevada, coupled with growing populations, have elevated the Wild West to be the next major political battleground," Roll Call writes. "The region will play a decisive role in Democrats’ ability to hold their Senate majority."

(Those three states will also likely decide the presidential race. Example: If Obama wins both New Mexico and Nevada, his path to 270 electoral votes is an easy one.)

CONNECTICUT: Democratic Rep. Joe Courtney says he will not run for the Senate.

INDIANA: "Indiana Treasurer Richard Mourdock will kick off his campaign against Sen. Dick Lugar Tuesday, setting up the longtime Republican lawmaker for a potentially competitive primary," Roll Call writes. "Mourdock told Roll Call that he will reveal a list of supporters that includes more than 75 percent of GOP county chairmen in the state."

NEW MEXICO: "Democratic Rep. Martin Heinrich is considering a run for Senate in 2012 following Sen. Jeff Bingaman’s announcement last week that he would not seek re-election in New Mexico, the House Member said Sunday," Roll Call says.

NEW YORK: Groundhog's Day in Upstate? "New York state Assemblywoman Jane Corwin was chosen Monday to be the GOP’s representative in the special election to replace Rep. Chris Lee (R) in the Empire State’s 26th district," per Roll Call. "The nomination of the establishment favorite, while celebrated by local Republican officials Monday night, drew an ominous warning from western New York tea party activists who immediately vowed to pursue a third-party candidate."