DENVER — Walker Stapleton, the Republican nominee for Governor, has picked State Rep. Lang Sias, R-Arvada, as his running mate.

Stapleton made the announcement for lieutenant governor at Wings Over the Rockies Museum on Wednesday morning in front of a fighter jet.

"I am pleased, I'm actually completely psyched to announce Colorado's next lieutenant governor, my friend Lang Sias," said Stapleton. "I needed to find the person that was the most competent, able and intellectually adept person that I could find, that I had a professional rapport with, that I had worked on controversial legislation with, that I knew could reach across the aisle, that I knew Democrats, by and large, held in high respect and high esteem, and Lang fit all of those most important criteria for me."

Sias is a former Navy fighter pilot and TOPGUN instructor, and a current FedEx pilot and State Representative for House District 27, covering Arvada and northern Jefferson County. He is married with three kids.

He was appointed to his House seat in 2015 after Libby Szabo resigned when she was appointed to fill a vacancy as a Jefferson County Commissioner.

Sias won his election in 2016.

State Rep. Lang Sias, R-Arvada
State Rep. Lang Sias, R-Arvada

He was up for re-election this year, but has to withdraw from the race to run on the gubernatorial ticket. He does not have to resign his seat in the interim.

"The reason that I elected to do this and that I was willing to give up running for a seat that I think I would have held rather easily, is that I believe in Walker Stapleton as great leader for Colorado going forward, and I also believe that the policies that a Polis administration would pursue would be very damaging to our state," said Sias.

Polis announced former state lawmaker Dianne Primavera as his running mate last week.

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State law requires the gubernatorial candidate to select a running mate within seven days of the election. That would have been July 3. That person has 30 days after the primary to accept. That would be July 26.

Stapleton's campaign told 9NEWS last week that it had offered the position to someone on July 2.

"Contrary to contrived political narratives, Lang and I have had this ongoing conversation about this now for a matter of weeks," Stapleton said when 9NEWS asked Sias to explain how and when he was offered to be the running mate. "Lang has a day job as an international FedEx 777 pilot, but we've had this conversation over a number of weeks, and we had planned to let everybody enjoy their Fourth of July holiday with their friends and families and make this announcement soon after."

"We had conversations going back, I would say, at least a month," said Sias.

Stapleton said he interviewed a "wide field of talented people" before offering the opportunity to Sias.

When Gov. John Hickenlooper selected Donna Lynne to be his new lieutenant governor in March 2016, he said she would become the state's CEO. Sias said his role is not yet firm.

"My role as lieutenant governor will obviously be at the discretion of our Governor, Walker Stapleton. I'm willing to take on whatever role he would like me to play," said Sias. "I do believe that having served for four years in the legislature and done it in a bipartisan fashion, I think there is probably a role for me to be played there in terms of working with legislators from both parties and both chambers on legislation that Gov. Stapleton would be interested in."

"We've seen from the current Governor that that role can expand and is malleable, and that is how it will be with Lang," said Stapleton.

According to a 2010 Denver Post article about Sias running for Congressional District 7, which he lost in a primary to Republican Ryan Frazier, Lynn Bartels wrote that Sias registered as unaffiliated when he moved to Colorado in 2000, switched to Democrat in 2003, then unaffiliated in 2006 and then registered as a Republican in 2007.

Bartels, who is now the spokeswoman for the Secretary of State's Office, which keeps that information, confirmed those dates for 9NEWS.

"I thought, probably foolishly, that the Democratic Party had room for people with the views of say, a John Kennedy, which I found out was frankly not the case," said Sias about his party affiliation switch. "I have had some conversations with people who, I would say, are on the more right-side of the party, and frankly, they've been extremely supportive."

Stapleton, Sias, Polis and Primavera all live in the metro area.

Last week, when asked about being able to represent all of Colorado, Polis touted his travels.

"Our first appearance together, we're going to be in Durango and Grand Junction and Delta (July 3). We're doing a health care listening tour in western Colorado. I represent parts of Western Colorado already, Eagle County, Grand County, but what's really important is to understand the diversity of needs in this state, and the issues facing families in La Plata County or Mesa County, are in some ways different than Denver and Jefferson County and Boulder County, but also in some ways the same, on that human level, that people just want what's best for their loves and themselves," said Polis.

When asked how people outside the metro area should view his ticket, Stapleton also answered by naming locations statewide.

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"Somebody who's committed to having Colorado in having a holistic view. As treasurer, I've traveled to all 64 counties in Colorado, spent an inordinate amount of time in rural Colorado, in the San Luis Valley, in Grand Junction, up north in Fort Collins, in the eastern plains, in La Junta and Lamar. And we will continue to spread that message of opportunity, I just have a partner to do it with," said Stapleton.

"Working in the legislature, with legislators from around the state, I think that's a tremendous resource to have. And I'm sure I'll be having conversations, whether it's (Rep.) Jim Wilson in Salida or (Rep.) Yeulin Willett or (Rep.) Bob Rankin or (Rep.) Jon Becker, I mean, there's tremendous resources around the state that, I think as a team, we have to draw on," said Sias.

Sias, like Stapleton, is from Connecticut, but said they didn't know each other then.

"Grew up at a different time and different places," said Sias.

When asked about his race against Polis, Stapleton gave what might be the most honest answer from a politician.

"I hope always to be an underdog and I hope to be the beneficiary of low expectations," said Stapleton.