COLORADO SPRINGS, Colo. - Just a few yards inside El Paso County, where an enormous sign announces that Interstate 25 is now known as Ronald Reagan Highway, it becomes clear that Colorado has a distinct conservative streak.

How conservative is it? Four years ago, when GOP presidential contender John McCain won 60 percent of the vote in El Paso County, Republicans declared themselves disappointed.

"It was below where we need to be," said Colorado Republican Party Chairman Ryan Call. "Your heavily Republican counties, you just have to do much better in terms of those margins."

Other Colorado counties deliver bigger slices of their vote to Republicans -- McCain won 82 percent in Cheyenne County, a rural area near the Kansas border -- but no area is more vital to a Republican hoping to win the Centennial State than El Paso, which, with more than 600,000 residents, is the state's most populous county.

"It is critical. It is crucial. If El Paso delivers a huge margin, we overcome some of the more liberal areas like Denver and Boulder," said Eli Bremer, chairman of the local Republican Party. "With a two-to-one Republican to Democrat voter registration advantage, we have to do that. It's not that we need to. It's not that we should. It's that we have to."

Democrats have a more relaxed perspective: El Paso County is an opportunity to irk their rivals and perhaps throw a monkey wrench into the GOP's statewide strategy.

"We have a lot of fun in what we do because we have nothing to lose and everything to gain," said Christy Le Lait, the county Democratic Party's executive director. "What happens here matters, even though we may be outnumbered."

With polls showing the race for Colorado's nine electoral votes as one of the country's closest, both President Obama and Republican Mitt Romney are fighting over the communities in the shadow of Pikes Peak.

Romney visited Colorado Springs on Saturday. Obama was scheduled to be there a few days earlier but canceled to deal with Superstorm Sandy.

The candidates' focus on Colorado so late in the campaign reflects a simple reality: To wrest Colorado from Obama, who won it by 9 percentage points in 2008, Romney needs to recapture much of the ground McCain lost. He can win here. George W. Bush won the state in 2000 and 2004 with a margin of at least 5 percent.

"Picking up some gains, whether it's in turnout or [among] people who voted for Obama in 2008, could be one way to win," said Michael Berry, a University of Colorado-Denver political scientist. "I would expect there to be swings back in the other direction."

While a Romney win in El Paso County is a virtual lock, Le Lait said area Democrats have been active in the contest's final days, wrapping up as many votes as possible before early voting ended Friday.

"People have made their choice, and they're starting to understand they better protect that choice," Le Lait said. "People are committed. They're scared of what their future could hold, and they want to make sure the president is re-elected."

But Call said Republicans are equally motivated.

"In 2008, there was not this level of enthusiasm," he said. "We feel like this year we're seeing enthusiasm."