In what his team has previewed as “an important speech” on Monday about the direction of the campaign and the messages he plans to promote going forward, Mr. Bush is returning to Florida, where he served eight years as governor.

During an address in Tampa, aides say, Mr. Bush will discuss his rejection of what he calls the “competing pessimisms” of the Obama era and will cite his experience as governor overcoming obstacles to conservative overhauls. He is expected to point to examples from his new book, “Reply All,” which will be released on Monday and details his prolific email habits as governor.

The text includes email exchanges with staff members, residents and others, recounting crucial moments of his tenure (natural disasters, the Terri Schiavo case, the 2000 election) and less momentous ones (constituent concerns over unisex bathrooms and a bill authorizing the creation of a state barbecue commissioner).