Rep. Mark Udall (D) on Monday filed papers to run for Colorado’s open Senate seat, making official what have long been his stated intentions for the 2008 cycle.

“I intend to run a campaign that breaks the old mold of bitter and partisan politics, in favor of one that is about bringing Coloradans together,” Udall said in a statement.

Udall reported raising $335,000 during the first quarter to finish with $1.5 million in the bank.

Sen. Wayne Allard (R) is retiring next year, and Republicans still are without an announced candidate in what is expected to be a heavily targeted race on both sides.

Former Rep. Scott McInnis (R) had created an exploratory committee, but then dropped out of the race only weeks later. Meanwhile, former Rep. Bob Schaffer (R), who lost the 2004 GOP Senate primary to beer magnate Pete Coors, continues to flirt with a Senate bid but has made no decision either way.

— David M. Drucker