Former Florida Governor Jeb Bush will join the attorney general for a statewide fly-around Monday, the first day of early voting. Mr. Bush endorsed Mr. McCollum earlier this year.
The GOP race has been thrown into turmoil as Rick Scott pours millions into the race for his own advertising and siphons support from the Republican base.
Former Florida Governor Bush has been touted as a possible presidential candidate in 2012. So far, the former governor said he has no plans to run.