Featuring fiercely contested primaries in both parties, the race for Colorado’s U.S. Senate seat–currently held by appointed Democratic Senator Michael Bennet–remains wide-open heading into the August 10 primary just ten days away.

A new poll conducted from July 27-29 by Survey USA for the Denver Post/9NEWS featured already voted/likely voters from both parties.

Bennet’s Democratic primary challenger Andrew Romanoff made up substantial ground in the poll since June, where he trailed by 17 points. Romanoff leads Bennet 48-45, within the margin of error. These results come on the heels of an “independent” poll released earlier in the week that saw Bennet with the slimmest of leads, 44-40, over Romanoff.

With a little over a week to go until voting in the primary closes (46 of 64 Colorado counties are implementing mail-only balloting), Bennet will call on his vast cash on hand reserves–$2.6 million–to make a final push against the insurgent Romanoff, who loaned his own campaign $325,000 this past week in a last-ditch effort to bring some semblance of funding parity to the Democratic primary.

For Republicans, the contest between Ken Buck and Jane Norton appears to have tightened, with Buck up 9 points over Norton, down from 16 in the same June Survey USA poll. Buck now leads 50-41. The rough-and-tumble GOP primary has taken its toll on both candidates, with Norton making Buck’s verbal gaffes the centerpiece of her comeback strategy and Buck the beneficiary of nearly $2 million in outside ads targeting Norton.

In the Survey USA poll of hypothetical head-to-head matchups, Buck ties Bennet at 43-43 and Romanoff 44-44, while Norton leads Romanoff 45-40, but trails Bennet 43-46.

Another poll conducted by a “major Republican firm” and mentioned by the Washington Post’s Chris Cillizza on Friday had Norton up 45-40 over Buck. Curtis Hubbard, political editor for the Denver Post, strenuously questioned the methodology and provenance of the anonymous/internal poll:

The media’s job — be it in print, on a blog, or on the air — is to report thoroughly, fairly and accurately. While that’s often a tall task in the heat of political campaign season, its a pretty simple one when it comes to polling. Pollsters also have a responsibility to be transparent, and we should question those who hide or fudge their work at the request or to the benefit of their client (To learn more, I direct you to the American Association for Opinion Research Code of Ethics).
So, here’s the challenge to anyone who wants to take issue with the Denver Post/9News poll when results are made public on Sunday: Put up or shut up. [emphasis in original]

Earlier in July, both Rothenberg Political Report and Cook Political Report listed Colorado’s Senate seat as a “toss up.”