As Jeb Bush attempts to revive his presidential campaign following another lackluster debate performance and increasing donor concerns, the former Florida governor scored a powerful endorsement in his home state. Richard Corcoran, who served as chief of staff to rival presidential candidate Marco Rubio when he was Florida House speaker, announced he will support Bush for president on Monday.

Corcoran is the Florida House speaker designate and a powerful Florida politician. While Bush has endured intense scrutiny in recent weeks due to his consistently  low polling average and inability to excite voters, he maintains he is in the race for the long haul. This latest endorsement, combined with his “Jeb Can Fix It” speaking tour Monday in Florida, is a sign that he remains serious about his 2016 bid.

“I have known Jeb Bush for over 20 years,” Corcoran said in a statement to and Politico. “As governor, Jeb Bush set the standard against which all other conservatives in this state are measured – no one in Florida would argue that. Jeb Bush always stepped up and was true to his principles, even if that meant facing difficult consequences. I saw him in moments when it would have been easy to cave to the special interests and just go along with the status quo; yet he never did.”

Although Corcoran emphasized his knowledge of Bush in his endorsement announcement Monday, he arguably knows Rubio on a similarly deep level. In addition to working as Rubio’s chief of staff, Corcoran ran state House campaigns for the Florida senator.

Rubio U.S. Republican presidential candidate Marco Rubio speaks at the Growth and Opportunity Party at the Iowa State Fairgrounds in Des Moines, Iowa, Oct. 31. Photo: Reuters/Brian C. Frank

Corcoran joins a large group of Florida politicians who have endorsed Bush for president in 2016. With Corcoran’s support, Bush has nabbed all but two recent GOP speakers of the Florida House of Representatives. The only two who have not endorsed the former governor are Rubio himself and Johnnie Byrd, who is not known as a Bush fan.

Bush will campaign with Corcoran during events Monday in Tampa, Orlando and Jacksonville.

“He is without question, the most courageous, conservative in this race,” Corcoran said of Bush. “That’s what I want in a leader, and what I know the electorate deserves. When the people of this country get to know the Jeb Bush that I know, they will have no doubt that he is the right choice to become the next president of the United States.”

In addition to his “Bush Can Fix It” tour this week, Bush released a 730-page e-book Monday called “Reply All,” which is a compilation of his email exchanges with Florida constituents during his time as governor. The one-time front-runner now sits at fifth place behind Donald Trump, Ben Carson, Rubio and Texas Sen. Ted Cruz, according to Real Clear Politics’ average of national polls. Bush’s team seems to hope the grassroots tour and book will liven up his public persona and provide a personal side to the candidate as they try to change the downward trajectory of their campaign.