Colorado Springs, CO -

As of Monday night, more mail-in ballots have been returned in El Paso County than any other county statewide in advance of Tuesday's primary election.

County election leaders say nearly 60,000 ballots were turned in to the El Paso County Clerk & Recorder. In Colorado all elections are vote by mail.

"Your vote actually may make the difference," El Paso County Clerk & Recorder Wayne Williams said. "At this stage, please don't mail your ballot because it won't get here in time. "You'll have to drop it off because we have to receive all ballots by 7 p.m. Tuesday evening."

One GOP race to keep an eye on is the contest in Congressional District 5. Incumbent Doug Lamborn takes on retired Air Force Gen. Bentley Rayburn.

On primary eve, Rep. Lamborn is in Washington, D.C., working on Veteran Affairs legislation. His campaign says Rayburn, having never held elected office, is too inexperienced for the job.

"Doug Lamborn has the proven conservative track record in this race," campaign spokesman Jared Rego said. "He doesn't just walk-the-walk, he talks-the-talk and voters can see that in his votes in Washington.

Rayburn touts his outsider status.

"We need more people who don't see politics as a career," Rayburn said. "People who haven't started right out of college spending their whole life in political office, who have no other experience to draw on."

In El Paso County there are 11 ballot drop-off locations.

In Pueblo, more than 17,000 were turned in as of 5 p.m. Monday

The GOP gubernatorial primary is the big statewide race to watch. Who will take on Governor Hickenlooper this November? The Republican contenders vying for a primary victory Tuesday night are Bob Beauprez, Scott Gessler, Tom Tancredo and Mike Kopp.