ASSOCIATED PRESS Tom Mauser, father of slain Columbine student Daniel Mauser, hugs Lori Haas, mother Emily Haas, who was wounded in the Virginia Tech shooting, at a Columbine Remembrance and Rededication ceremony on the 10th anniversary of the Columbine attack at the Capitol building in Denver, Colo., in April 2009.

Just last month, Tom Mauser watched as Andy Parker, father of slain TV journalist Alison Parker, talked about his loss on CNN.

Parker's daughter Alison, who worked at the CBS affiliate KBDJ in Roanoke, Virginia, was shot and killed alongside photojournalist Adam Ward by a disgruntled former employee of the station.

​Tom Mauser says he's glad to hear Parker commit himself to the issue for the long-term, but he knows well the uphill battle Parker faces. Mauser's son Daniel was gunned down at Columbine High School in 1999.

For the last 16 years, Mauser, who's a spokesperson and board member of Colorado Ceasefire, has fought, with varying degrees of success, to get lawmakers to require background checks for every gun sale in the state and impose a ban on high capacity ammunition magazines.

(Courtesy Tom Mauser) Tom Mauser with his son Daniel.

In the aftermath of the Columbine shootings, Colorado passed a law to require background checks at gun shows. But since then, Mauser says, the issue has become a political hot potato where lawmakers fear repercussions if they speak in favor of gun control.

"I realized early on, that you have to be in this for the long term," he says.

Click on the audio above to hear Mauser's conversation with Andrea Dukakis. Edited highlights are below.

How he became an activist:

"For the first 10 days, I didn't speak to the media at all. I was just in shock. [...] And then suddenly, I was so angry knowing that the NRA was meeting in town that I went and spoke in front of 12,000 people.

[...]It can be shocking. After I spoke, I suddenly realized I'm going to start getting calls from the media, I'm going to start getting people who are angry at me. You really have to be prepared for that.

[...]It can get pretty overwhelming. When you become an activist, you tell your story a lot. You live that story every day anyhow, it's not like you don't think of your loss. But when you go in front of other people and speak about it, it's so much more. "

On measured conversations with gun rights advocates:

"[It doesn't happen] very often, unfortunately.

Over the past year, for example, I've been speaking at a number of churches, churches who are willing to take on a contentious issue like this. When I speak at churches, there will sometimes be someone there who's pro-gun, maybe not extreme, but at least who presents a different perspective. In that safe environment, we've had some really good conversations.

[...]I think we can find common ground on a number of issues. In fact, I think over 70 percent of NRA members support background checks. If you really get to the heart of it, most people are in the middle on this issue."

Why he doesn't contact those who are in grieving after a shooting