The Libertarian Party, meanwhile, appears likely to field a candidate. Rick Stanley, a Denver businessman, said Tuesday he will seek the party's nomination.

Rumors had circulated that the Greens might jump into the race. Last year, Boulder activist Ron Forthofer ran on the Green ticket against Democratic Congressman Mark Udall. While Forthofer garnered just over 4 percent of the vote, his challenge was considered serious enough that the Democratic Party flew in heavy-hitters such as Rep. Barney Frank, D-Mass., to persuade voters on the left to stick with Udall.

Greens say they aren't enthusiastic about the two Democrats being discussed as challengers to Allard - former U.S. Attorney Tom Strickland and Denver Mayor Wellington Webb. Still, a Green challenge does not appear to be in the works.

"We're looking at a lot of interesting races next year, and we may choose to put our energies elsewhere," said Dean Myerson of Boulder, a former state co-chairman of the party. "There's a good chance we'll leave that race alone."

Myerson emphasized he was not speaking in an official capacity, as the party has made no formal decisions. He predicted that Greens may choose to run in a number of state legislative races or put their efforts into possible ballot initiatives.

Grassroots initiatives being discussed among progressive activists include growth control, campaign-finance reform, electoral reform, health-care reform and mandatory labeling of foods containing genetically engineered ingredients.

"We've got a limited number of resources, and we want to focus them in areas where we can do the most good," Myerson said. "Some candidates are seriously considering some state House races in the Front Range area."

Stanley, who runs a small family business, said he's new to politics and the Libertarian Party but wants to challenge the two major parties, which he accused of representing big government.

"Democrats and Republicans have basically dropped the ball and taken government in a direction it was never intended to go," Stanley said.

The result, he said, is that most ordinary people are forced to work too hard in order to pay their taxes.

"I've been working hard all my life, and it's never enough," Stanley said. "The reason I'm running is I don't want my kids and grandkids and their kids to have to go through this stuff."

While the Libertarian Party is seen by some as taking votes from the GOP, Stanley said he wasn't at all concerned about the possibility of "spoiling" the race and helping the Democratic candidate win.

"I don't care," he said. "There's no such thing as a good Republican or a bad Republican. There's no such thing as a good Democrat or a bad Democrat. I don't believe in their philosophies."

Patrick West, state chairman of the Natural Law Party, said his party hasn't made any plans yet but hasn't ruled out any options.

"I'm hoping that we'll be able to run someone in that race," West said.

If not, the party may endorse another minor-party candidate, he said.

West said Natural Law Party activists are also likely to get involved in ballot initiatives.

"There's just going to be a ton of good initiatives," he said.