08/09/2010 02:50 pm ET Updated May 25, 2011

Colorado Senate Races Still Close Headed Into Tuesday's Elections

One day before the Colorado primaries, both parties' Senate races are still too close to call. That's according to Public Policy Polling (PPP), which, on Monday, released the results of a survey conducted over the weekend that showed incumbent Democrat Michael Bennet with a slight lead over challenger Andrew Romanoff, and Republican Jane Norton narrowly edging her opponent, Ken Buck.

The poll showed Bennet with a 49-43 lead over Romanoff among likely Democratic primary voters, with 9% still undecided.

Like most polling services, PPP shows Romanoff surging since the last time the company surveyed the race in May. Bennet is coming off a rough week in which he's been on the defensive after the New York Times criticized a financial deal he backed as superintendent of the Denver Public School system.

PPP notes that, with 9% still undecided, "it's close enough that this race could go either way tomorrow but a Bennet victory is more likely."

As of Friday afternoon, the last day to mail in ballots, 30% of Democrats with mail-in ballots had already sent in their vote.

On the Republican side, Jane Norton leads Ken Buck 45-43, which, as PPP points out, is the first public poll in many weeks that has had Norton in the lead.

The survey showed that the support among the GOP electorate is largely divided on racial lines:

"Among voters who think the party's too liberal, which account for 39% of the electorate, Buck leads 53-41. But with the smaller groups that think the party is ideologically about right or even too conservative, which account for 35% and 15% of the voters respectively, Norton has leads of 51-36 and 52-34."

PPP's May poll showed Buck down by 5 points.

As of Friday, 32% of Republicans had returned their mail-in ballots.

The survey, which questioned 448 likely Colorado Democratic primary voters and 767 likely Republican primary voters, had a margin for error of +/- 4.6%.