According to a Colorado Peak Politics source, ballot returns as of this AM have Republicans leading. This includes mail-in ballots returned since they were mailed out on Monday, October 15, but not early voting numbers, which began yesterday.
According to the most recent Denver Post poll of Colorado, Governor Romney is leading among Unaffiliated/Independent voters 43-39.
Ballot returns as of the morning of October 23:
Democrats – 61,761
Republicans – 70,826
Unaffiliated – 37,687