At the end of the day I just don't see how a liberal can clear Kerry's 47% here.
John Kerry is a fairly unlikeable guy from a state 2,000 miles away from Colorado and he still got 47%. Udall is a likeable local guy who connects with the average joe.
In addition, as a result of Bush's disastrous presidency and the unpopularity of the war, the state of Colorado has shifted left (or at the very least the centrists and independents are now voting for the Democrats instead of the Republicans).
It's not the same electorate as in 2004. Views have changed tremendously, and demographic changes have also favored the Democrats. It's unfair to compare 2008 to 2004, two completely different political atmospheres.