DENVER -- Democratic congressional candidates Joan Fitz-Gerald, Jared Polis and Will Shafroth have gathered in Boulder for a debate in their bruising three-way primary campaign.

The debate got under way Friday in the packed Boulder City Council chambers.

Polis said the election is important because energy, the economy, Iraq and other major issues can be settled only at the national level.

Shafroth said he's worried that the next generation will inherit an endangered environment and breakdowns in the education and health-care systems.

Fitz-Gerald said the main issue in the election is quality of life.

According to voter registration figures from the secretary of state, the district is heavily Democratic, with 149,000 Democrats and only 117,000 Republicans as of April. Pundits say historically the winner of the primary goes on to Congress.

But a high number of unaffiliated voters -- 172,000 -- could be a determining factor this year, giving a dark horse candidate a chance of beating the Democratic primary winner. Though none have entered the race so far, only about 1,000 signatures are needed to get on the ballot and they could qualify after the primary.