Colorado sent Democrat Ken Salazar (search) to the Senate on Tuesday, opting for the moderate state attorney general over Republican beer baron Pete Coors (search) and giving the Democrats a seat once thought to be solidly in the GOP column.

Salazar becomes the first Hispanic U.S. senator in more than a quarter century.

His victory capped a nasty campaign stoked by more than $15 million in combined spending devoted to winning the seat being vacated by Republican Sen. Ben Nighthorse Campbell (search). It was the most expensive campaign in Colorado history.

Salazar, a fifth-generation Colorado rancher, tapped a populist theme, saying he understands the struggles of the working class and would create jobs and boost education funding. He also said he would be the best candidate to improve homeland security after serving two terms as attorney general.

Coors, whose great-grandfather founded the Golden-based Adolph Coors Co., stressed his business experience and belief in low taxes, small government and a strong defense.

National parties were watching Colorado closely in part because Democrat John Kerry was hoping to get a boost from Salazar's appeal to fellow Hispanics. Both parties backed millions of dollars in advertising, and a string of heavy-hitters, including President Bush, took to the state to lock up voters. In the end, Bush won a relatively comfortable victory.

The presidential candidates also had an interest in Colorado because the state was deciding a measure that would immediately scrap the winner-take-all system for its nine electoral votes and award them proportionally based on the popular vote. Several legal challenges were expected if the measure passed.

Last spring, it looked like Republicans wouldn't have to worry about the Colorado Senate seat. But Campbell threw the race wide open when he abruptly announced his retirement, citing health concerns. A string of Democrats bowed out when Salazar, long considered a 2006 gubernatorial hopeful, declared his candidacy.

Coors, 58, was drafted by GOP leaders concerned that former Rep. Bob Schaffer was too conservative to win a statewide election.

The campaign quickly turned bitter. Among other things, Salazar, 49, was labeled a friend of the trial attorneys' lobby, while Coors was called a shill of big business.

Salazar did not appear in public with Kerry until late October, suggesting he was avoiding the presidential candidate because he was in a close race in a GOP-leaning state. Salazar blamed scheduling problems.