Michelle Badger votes Tuesday at a polling center at Meiklejohn Elementary School in Arvada.
Michelle Badger votes Tuesday at a polling center at Meiklejohn Elementary School in Arvada. (RJ Sangosti, The Denver Post)

Colorado turned a shade bluer Tuesday, but the state's largest group of voters — those unaffiliated with any political party — make it unlikely either major party will dominate for the foreseeable future.

By helping lift President Barack Obama to re-election and handing control of the state House to the Democrats, Colorado lent support to Democratic arguments that the state's changing electorate — especially in the Denver suburbs — favors them.

At the same time, the status quo appeared to be holding in Colorado's congressional makeup despite redistricting that made three seats more competitive. The U.S. House delegation was projected late Tuesday to remain 4-3 tilted toward Republicans, demonstrating the power of incumbency when neither party is dominating nationally.

"When you really dig into it, we're as purple as ever," said Democrat strategist Mike Melanson of OnSight Public Affairs, who has managed campaigns for Sen. Mark Udall and Gov. John Hickenlooper. "Overall, it might be a Democratic night. But you know what? In two years, it will probably be a Republican night. We're just that kind of state."

Obama's win in Colorado runs counter to recent history. Colorado's electoral votes had gone to Republicans in nine of the previous 12 presidential elections. The Democrats who prevailed here — Lyndon Johnson in 1964, Bill Clinton in 1992 and Obama in 2008 — did so as part of landslide victories, not in a closely contested race like this one.

The last time Colorado supported a Democratic incumbent: Franklin D. Roosevelt in 1936.

"The Democrats will feel like they have the formula," said Denver pollster Floyd Ciruli. "Their fundamental argument is they are an ascendant party because of the state's changing demographics."

Colorado long was solidly Republican country. The state turned a deeper shade of red in the 1990s, framed by the passage of tax limitation measure the Taxpayer's Bill of Rights, or TABOR, in 1992.

By 2002, Republicans controlled the governor's mansion, both U.S. Senate seats, five of the seven U.S. House seats and both chambers of the General Assembly. Just six years later, the opposite held true — Democrats held all those cards.

Analysts point to a combination of factors for the swing: an influx of college-educated whites and Latinos to fast-growing areas; a Republican shift to the right that alienated some suburban voters; a Democratic political strategy of fielding moderate candidates who appeal to independent voters; and the influence of a small group of wealthy liberal donors backing Democratic candidates and causes.

In 2010, in a wave election for Republicans, the state reverted to purple, with both Republicans and Democrats prevailing in key races.

Robert Loevy, a retired Colorado College political science professor, said his research found Colorado is the only state west of the Mississippi River and east of the West Coast states becoming more Democratic. If trends hold, he expects Colorado to become a true blue state in 10 to 20 years.

"I think the Republicans are still going to win a lot of elections, and there could be national Republican sweeps that will help Republicans here," Loevy said. "But the long-range trend is very clear."

Loevy cautioned against reading too much into congressional and statehouse results as a barometer of the state's political profile because of the outsized role redistricting plays in those races.

Jeremy McKenna, left, talks with election judge Jodi Litchfield at the Civic Center in Englewood on Tuesday.
Jeremy McKenna, left, talks with election judge Jodi Litchfield at the Civic Center in Englewood on Tuesday. (Craig F. Walker, The Denver Post)

While demographic changes favor Democrats, there's no guarantee demographics hold, said Melanson, the Democratic strategist. Catholics once were reliably Democratic and now are swing voters, and the same could eventually hold for true for Latinos, for instance.

"The one thing we know," Melanson said, "is change."

Robert Duffy, a Colorado State University political scientist, said the results Tuesday show Republicans in Colorado have a "real problem with unaffiliated voters."

"You look at early vote numbers, and they show Republicans are up by 35,000 votes or so in votes returned," Duffy said. "But then you look at the results on election day, and it's like, 'Whoa, Obama must have won the unaffiliated votes.' "

In a state divided by thirds into Democrats, Republicans and unaffiliated voters, that makes it impossible to win a statewide election, he said.

Denver pollster Ciruli notes that Colorado ranks in the middle nationally in partisanship, ideology and religious identification.

The state can claim voters committed in their beliefs — strong liberals backed Obama over Hillary Rodham Clinton in the 2008 caucuses, and Colorado Republicans backed conservative Rick Santorum over Mitt Romney in caucuses this year — the real power lies in the middle.

"While Democrats will see some advantage, the state will remain very close," Ciruli said. "The decade of the 1990s was an anomaly in getting conservative but from 2004 to 2008 was also an anomaly, and now we are getting back to the mean. And the mean is very, very competitive."

Eric Gorski: 303-954-1971, egorski@denverpost.com or twitter.com/egorski