DENVER — Signature collection is one way for candidates to qualify for election ballots, and that process is going on trial Tuesday morning.

Five voters in Congressman Doug Lamborn's Fifth Congressional District in southern Colorado, are suing over the signatures he turned in to qualify for the primary ballot in June. The voters claim that some of the signature collectors are not Colorado residents and don't meet the qualifications to collect signatures.

In a twist, Republican gubernatorial candidate Walker Stapleton has filed paperwork in the court case to intervene and have the case against Lamborn dismissed. Why? Because he hired some of the same signature collectors being challenged in the Lamborn case.

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Lamborn, a six-term Republican, has faced a primary challenge just about every two years since he was elected in 2006.

Candidates can qualify for the ballot by collecting a set number of signatures or by going through the party's assembly process and garnering at least 30 percent support.

Lamborn skipped the Fifth Congressional District assembly, and instead turned in signatures. He needed 1,000 registered Republicans in his district to qualify. The Secretary of State's Office certified 1,269 valid signatures.

The lawsuit seeks to have more than half of those signatures tossed by proving the people who collected the signatures aren't Colorado residents. If a judge were to agree that the circulators do not meet the residency criteria, they could throw out as many as 696 of Lamborn's 1,269 signatures. That would leave him with 573 signatures, well below the required amount, with no other avenue to qualify for the ballot.

"One of them has a house in California, has a wife out there, we clearly don't think he's a resident just sharing space with somebody who owns a house," said Michael Francisco, the attorney representing the five voters. "Where's your drivers' license? Where's your property? What other houses do you own or lease? How much time do you spend at them?"

Let's stop here and ask the obvious question: SO WHAT?

Who cares who collects my signature? Why isn't it just my signature that counts?

"It goes to the integrity of the election process, so Colorado and other states have this legal requirement. Everybody knows ahead of time what the rules are and you have to follow the rules. What if a candidate turns in 950 signatures instead of 1,000?" said Francisco. "We don't want somebody to claim they're a registered voter if they just visit or come to Colorado a week before the election."

Six of the signature collectors for Lamborn, and also Stapleton, recently registered to vote at the same home in Thornton.

"There's nothing wrong at all for folks that might be collecting signatures to take jobs here temporarily and then go other places and return to Colorado time and again, and that's the case in the case of most of these circulators," said Lamborn Campaign Attorney and former State GOP Chairman Ryan Call. "The questions of who the circulators are, what they're voter registration is or whatever, is really not as important as the actual voters that are signing those petitions."

Stapleton has preemptively intervened in the case, since a challenge to Lamborn's signature collectors are essentially a challenge to his as well, even though his signatures haven't been challenged.

In his motion to dismiss Lamborn's case, Stapleton's attorney sums up their position by writing, "elections should be decided by voters, not lawyers."

"Have you amended your lawsuit to include Walker Stapleton?" 9NEWS reporter Marshall Zelinger asked Francisco.

"No," he said.

"Why?" asked Zelinger.

"We are prosecuting the lawsuit we have on Tuesday. If there's a separate challenge to Walker, that would be brought probably in a separate proceeding," said Francisco.

The hearing challenging Lamborn's signatures is at 9 a.m. in Denver District Court at the City and County Building.

9NEWS reporter Marshall Zelinger will be at the hearing. You can follow his updates on Twitter @Marshall9NEWS and on Next with Kyle Clark.