In a year where the insurgents-versus-establishment theme has played out repeatedly in Republican primaries, Democrats have their own insurgency in Colorado. Former state legislator Andrew Romanoff has  mounted a strong primary challenge to Sen. Michael Bennet, who was hand-picked to fill the seat vacated when Obama tapped Sen. Ken Salazar as his Secretary of the Interior. The mostly mail-in primary concludes next Tuesday, and a recent poll showed Romanoff surging. 

President Obama has already headlined one event in Denver for Bennet, and last night called into a “tele-town hall” conference call that reportedly reached more than 20,000 Colorado Democrats:

White House officials altered the president`s schedule Tuesday to include Obama`s participation, the first time the president has done a virtual town hall with any Democratic candidate.
Obama spoke for six minutes of the 54-minute call. . . .
Obama`s appearance was a recognition of the toll on Bennet taken by a recent spurt of negative ads portraying him as a corporate raider when he worked for Colorado billionaire Phil Anschutz, a toll conceded Tuesday by White House senior adviser David Axelrod.
But Axelrod said Bennet will “prevail in the end,” justifying the strong backing the incumbent has received from the White House almost since he was appointed in January 2009 — including fundraising, an early endorsement by Obama and visits to Colorado by several Cabinet members. . . .
And some analysts have suggested that Bennet is taking a risk by associating himself too much with an unpopular president if he makes it to the general election.

Meanwhile, in Colorado Republican Senate primary, polls show establishment-backed Lt. Gov. Jane Norton is trailing former Weld County prosecutor Ken Buck, a conservative who has strong support within the Tea Party movement. Norton, sister-in-law of GOP political consultant Charlie Black, has started airing attack ads against Buck and is bringing in John McCain to campaign for her.