A new SurveyUSA poll sponsored by the Denver Post and 9News shows challenger Andrew Romanoff has closed a 17-point gap with Senator Michael Bennet with just over a week to go before the Colorado primaries.
The poll, which had a 4.3% margin for error, showed Romanoff, the former Speaker of the Colorado State House, with a 48-45 lead over incumbent Michael Bennet.
A similar SurveyUSA poll commissioned by the Post and 9News in June showed Bennet with a 53-36 lead over Romanoff.
As the Post notes, the primaries have turned "increasingly negative" since the last poll was conducted, with the Romanoff campaign taking exception to a Bennet mailer claiming the former speaker supported privatization of Social Security.
Romanoff, meanwhile, has launched a series of negative ads attacking Bennet, the latest and most controversial of which accused the Senator, a former employee of billionaire Phil Anschutz, of "looting" a billion dollars from a cinema company.
Democratic tempers erupted into a shouting match on Saturday, when Romanoff supporters crowded sidewalks outside the state capital in order to interrupt a Bennet campaign event during which the Senator responded to Romanoff's latest attack.
The SurveyUSA poll also showed tightening of the Republican Senate primary over the course of the last month, although Ken Buck still had a 9 point lead over opponent Jane Norton. The June Poll showed Buck with a 16-point lead over Norton.