Sen. Michael Bennet (D-Colo.) fell to former state House Speaker Andrew Romanoff in Tuesday night's precinct caucuses, raising new hope for Romanoff's campaign in their primary.

National Democrats, who are supporting Bennet, worked hard to lower expectations in advance of the caucuses, which basically function like straw poll of activists. In the end, Romanoff's 51-42 victory was substantial but not overwhelming.

Another establishment favorite could be headed for a loss on the GOP side, with former Lt. Gov. Jane Norton falling narrowly to Weld County District Attorney Ken Buck.

This post has been updated. AP is reporting that Buck has beat Norton, but official results from the state GOP show him leading her 37.86 percent to 37.74 percent with 6 percent of precincts still to come.