The battle between Democrat John Salazar and Republican Greg Walcher for an open U.S. House seat in a western Colorado district the size of Florida was too close to call late Tuesday, held up by slow returns in a key county.

Salazar spokesman Jim Merlino said results were unavailable in Garfield County, home to some 28,000 registered voters. A woman who answered the phone in the county clerk's office said the delay was caused by having to unfold and count absentee ballots. Salazar had 127,856 votes, or 51 percent, and Walcher had 114,246 votes, or 46 percent. Unaffiliated candidate Jim Krug had 3 percent.

The race to succeed retiring GOP Rep. Scott McInnis was one of the most closely watched in the country, identified by Democrats as a top opportunity in their bid to pick up 12 seats and regain control of the House. Pollster Floyd Ciruli said GOP officials were originally lukewarm toward Walcher, but came through with financial support in the last few weeks of the campaign.

Both sides wound up spending about $8 million on the race, making it one of the top 10 in the country.

"This was definitely ground zero for congressional races," Ciruli said.

Salazar, a one-term state lawmaker and the brother of attorney general and senator-elect Ken Salazar, tried to make an issue out of Walcher's support for Referendum A, a plan to build major water projects on the Western Slope.

The $2 billion financing plan for water projects failed miserably last year, with Western Slope voters fearing it as an attempt by the heavily populated Front Range to steal their water.

Walcher brushed off the attack, saying people in his district this year were more concerned about taxes, federal regulations on land use and family values. A sharp critic of the Endangered Species Act, Walcher said his former job as the head of the state's natural resources department gave him the best perspective to solve problems.

The peach orchard farmer also said logging bans are turning forests into tinderboxes -- an indirect play for supporters of McInnis, one of the major proponents of President Bush's forest thinning program. And he offered himself as the conservative values choice, favoring a ban on legal recognition of gay marriage.

Salazar, a potato farmer from the San Luis Valley, said some of the television ads against him bordered on racism by suggesting he would support an open door policy for illegal aliens. One showed shadowy figures climbing fences in the background.

"I believe they were trying to make this a race issue. I really find it offensive. I thought this was a thing of the past," Salazar said.

Walcher, meanwhile, complained about ads criticizing him over a deal he made as the state's natural resources chief to pay a Utah firm for saving money in his department. The deal also allowed the firm to collect for new fees they proposed, and the contract was ordered to be renegotiated. Walcher said he saved the state money with his plan.