Gillespie was a former aide to House Majority Leader Dick Armey (R-Texas) and played a pivotal role in drafting the Republican "Contract With America" in the early 1990s. More recently, he worked on President George W. Bush's reelection campaign and chaired the Republican National Committee during the 2004 election cycle.

It was during that time that Gillespie made ties with some of the leading figures within the Romney campaign, including campaign manager Matt Rhodes. But Gillespie's addition is a signal that the Republican establishment is formally embracing Romney as he emerges from a sometimes-bitter primary fight, and that Romney is now willing to cede more control of his campaign to the national party.

“I’m excited to join Mitt Romney’s campaign team. His plan to reduce taxes, balance the federal budget, strengthen our national security and protect innocent human life stands in sharp contrast to the ruinous policies of President Obama. His record of strong leadership as governor and proven history of great accomplishment in both the public and private sectors show he has the ability to make the tough decisions needed to be a good president, which is sadly missing right now," Gillespie said in a statement.

Gillespie should also provide ties to important outside groups, including American Crossroads, a conservative political action committee primed to spend millions to support Republican efforts in November. Gillespie has served as an adviser for the Karl Rove-helmed group.