The two held a joint press conference in Kearney on Thursday.
Heineman says three key issues were part of his decision: experience, economic development and education. He says Bruning will be ready on day one, touting his 18 years in state government as a state senator and attorney general.
The governor says he's been thinking about the race for a long time but decided now is the time to speak out, and Bruning says he's grateful for the support.
"As they're going to the polls on Tuesday I hope they think about Governor Heineman's endorsement, so that's why I'm so excited about it," said Bruning. "It's a close race, a lot of Nebraskans are still making up their minds. By some estimates almost 20 percent are still deciding what to do; I want to earn their votes."
"The last week or so it's really intensified. Everywhere I go Nebraskans are asking me 'Governor, where do you stand on the Governor's race? Help us, let us know who you support,'" said Heineman. "So I decided to stand up and share with Nebraskans in supporting Jon Bruning."
Bruning says despite the big endorsement, he's still going to run like he's ten points behind.