Bad news for Republicans is trickling out of Missouri, where Kit Bond, the four-term Republican senator, is retiring. What would have been a relatively safe seat in 2010, in a state McCain narrowly carried (with less than 50% of the vote), will now be open.

Bond is one of only two statewide Republican officials, the other being Lieutenant Governor Peter Kinder, who is now getting looked over as a possible Senate candidate. Other potential GOP contenders are former Rep. Kenny Hulshof, who lost last year’s gubernatorial election to new Gov. Jay Nixon (D), Rep. Jo Ann Emerson of southeastern Missouri and Rep. Sam Graves of the St. Louis suburbs, who crushed top Democratic recruit Kay Barnes last year.

The leading Democrat has to be Robin Carnahan, the Missouri Secretary of State. A mid-2008 poll showed her tied with Bond in a potential 2010 match-up — any trial heat with the leading Republicans will likely show her ahead. She’ll probably be lobbied to get into the race as vigorously as Sen. Claire McCaskill (D) was lobbied by Sen. Chuck Schumer (D-N.Y.) four years ago.