FORT COLLINS--On a Saturday afternoon, Mildred Weidemann had backed her car halfway out of her driveway before Chris Longo stopped her to ask who she planned to vote for November.

"I'm not gonna tell you," the 74-year-old Weidemann answered firmly before continuing on her way.

"I get that answer a lot," Lombo explained as Weidemann drove away. "They say their vote is private, and I try to respect that."

Longo, a 24-year-old Loveland resident, is one of 20-25 canvassers working for Defenders of Wildlife in Fort Collins, Loveland, Longmont and Greeley to promote Democratic candidates Barack Obama, Mark Udall and Betsy Markey.

On average, Lombo said he knocks on 80-120 doors and targets 140-150 voters during each 6-hour shift to gauge support for candidates and sway voters on the fence about supporting Democrats.

As the 4th Congressional District has become one of the most competitive House races in the country, Defenders has become the leading independent group against U.S. Rep. Marilyn Musgrave (R-Fort Morgan).

Already, the group has spent almost $2 million against Musgrave, most of it going towards filling TV airwaves with advertisements bashing the three-term incumbent.

The group also promotes Udall's Senate campaign -- though unlike in the 4th Congressional District race, the group's mailers and signs promote Udall rather than attack Schaffer.

Defenders of Wildlife Action Fund came on the political scene in 2006, when it led a successful campaign to oust U.S. Rep. Richard Pombo (R-Calif.), who as chair of the House Resources Committee had long been a leading target of environmentalists.

Liam Flynn, lead canvass director for Defenders of Wildlife, said he thinks Defenders is targeting Musgrave this year with the same intensity the group did against Pombo in 2006.

Musgrave has certainly taken notice, lashing out at the group several times during a 4th Congressional District debate last week in Fort Morgan.

 "You can be sure that the Defenders of Wildlife Action (Fund) actually hate our rural way of life out here in Colorado," Musgrave told her hometown crowd during the debate.

Defenders also got in hot water last month for hiring two minors from Loveland as canvassers. Defenders campaign manager Ed Yoon said hiring the underage canvassers was "a mistake," according to the Fort Collins Coloradoan.

Defenders of Wildlife's voter targeting system this year, like other independent political groups, is much more sophisticated than in past elections. Each time he heads out to canvass, Longo is assigned a list of not only specific houses in a given neighborhood, but specific residents of that household.

Lombo said he's found that while a number people he's talked to buck their party affiliation about who they support in the presidential race or the 4th Congressional District race, most people he's interviewed stick to their party line when it comes to the U.S. Senate race between Republican Bob Schaffer and Democrat Mark Udall.

Flynn said that Markey's name ID has gone up since the group began canvassing in July: these days, about 40 percent of voters surveyed by the group know Markey's name, he estimated.

Lombo, who's been canvassing for Defenders in Colorado since July, said going door-to-door has helped him to be able to read people more quickly and easily.

"I can now discern within a matter of 5 seconds the matter of tempo, a slight difference in tenor, and the approach (I) need to take," Lombo said. "It's something that becomes something of second nature."