Diaz, who co-founded FP1 Strategies with Downs, confirmed their hires Monday.
Sally Bradshaw, a top Bush adviser, said Diaz and Downs will focus on promoting Bush's economic pitch.
"We're excited Jon and Danny are joining our team. Their expertise and experience will be critical to communicating Governor Bush's conservative ideas for greater economic growth and opportunity," she said.
The enlistment of Diaz and Downs, first reported by CNN, gives Bush’s PAC two more well-known GOP operatives to guide his expected bid as it ramps up its messaging and advertising efforts.
Diaz has worked for the GOP presidential nominee in each of the last three cycles, including as a communications aide to Sen. John McCain (R-Ariz.) in 2008 and as a senior adviser to Mitt Romney in 2012. He has also worked for the Republican National Committee.
Downs worked for George W. Bush’s presidential campaigns, and as an ad producer for tea-party favorites such as Sen. Ted Cruz (R-Tex.) and Sen. Rand Paul (R-Ky.). In 2012, he worked for then-Texas congressman Ron Paul’s presidential campaign.
The Washington Post profiled Downs in 2011 as “the man behind Ron Paul’s ads.”
On Wednesday, Feb. 4, Bush will speak at the Detroit Economic Club. The event will mark his first recent trip to Michigan, a key primary state in the race for the Republican presidential nomination.