Tim Walz's 17-year-old son Gus in floods of tears as his dad takes the stage to accept pick as Kamala Harris' running mate

It was an emotional moment for the Walz family as they watched their patriarch accept the Democratic vice presidential nomination. 

Tim Walz's son Gus shed tears, while daughter Hope made the heart symbol and mouthed 'love you.'

'That's my dad,' Gus, 17, shouted as he stood up and pointed at his dad on the convention stage.

It was his tearful moment that captured hearts around the country and all over social media. The two kids sat in the front row of the convention with their mom Gwen as their dad made his debut on the national political stage.

Hope Walz, 23, took photos as her dad spoke. After Walz wrapped his remarks, his family joined him on stage for hugs and waves to the crowd.

Tim, 60, and Gwen Walz, 58, have been public about their struggle with fertility and how they used fertility treatements to concieve their two children.

Walz, the governor of Minnesota, referenced that time in his remarks.  

'This is personal for Gwen and I. If you have never experienced the hell that is infertility, I guarantee you you know somebody who has,'' he said. 

'I remember praying each night for a phone call and the in your stomach when the phone would ring and the absolute agony when we heard treatments didn't work. It took us years but we had access to fertility treatments. When our daughter was born, we named her Hope.'

He added: 'Hope, Gus, and Gwen, you are my entire world, and I love you.'

His family stood to cheer him. 

Gus has a non-verbal learning disorder, ADHD and an anxiety disorder, the Walz told People magazine. 

Hope Walz is a frequent presence on her dad's social media accounts, including a viral video Walz reposted last Thanksgiving in which he tries to convince his daughter to eat some turkey.

'I'm vegetarian,' Hope Walz says in the video, pointing out turkey is meat.

'Not in Minnesota. Minnesota is special,' Walz replied. 

That moment got airplay at the convention on Wednesday. Gwen Walz narrated a video telling the story of their family, including how the couple met when they were both high school teachers.  

Are youThe Walz used a treatment known as intrauterine insemination, or IUI.  IUI is often attempted before IVF but doesn't face the same level of political controversy because it doesn't risk destroying unused embryos that anti-abortion advocates say equate to unborn children.

Walz spent little time in his speech talking about his time as a politician, which included years in Washington as a member of Congress and his tenure as governor of Minnesota.

Instead he focused on his time as a teacher and coach, even wrapping his speech with a pep talk that harkened back to his coach days. 

'There will be time to sleep when you are dead. We are going to leave it on the field. That is how we will keep moving forward.'