In a sign of turmoil in Marco Rubio’s underdog campaign for U.S. Senate, two of his top campaign staffers are dropping off the campaign. Campaign manager Brian Seitchik will leave the payroll in a week,  while fundraising consultant Ann Herberger will no longer be Rubio's chief money raiser.

With Republican frontrunner Charlie Crist trouncing Rubio in fundraising and Rubio trying to bat down rumors he’ll drop out to run for attorney general, the staff shakeup is likely to fuel new questions about Rubio’s long-term viability.

The Miami Republican downplayed the staff changes, saying it merely reflected the campaign’s need to run an unconventional, grass roots campaign against Crist. “This is not a purge or anything, quite the contrary,’’ Rubio said, while campaigning Thursday night in Pasco County.

For now at least, Rubio is running a campaign without a day to day campaign manager or professional fundraiser, though he's also saving Herberger's $20,000 monthly cost. He said his scheduler will also serve as finance director for the time being, and former Dick Armey adviser Pat Shortridge will serve as a senior advisor to the campaign.

Said the Rubio campaign: "At this point, Speaker Rubio believes it is necessary to click the reset button in certain areas of the campaign. He based his decisions on current realities that weren't evident when the campaign was organized earlier this year (background: before Crist seemed interested, it seemed like he'd be running against Connie Mack or Vern Buchanan).

"Up until now, we have been guilty of trying to run certain elements of the campaign in a traditional fashion when, in reality, this is a hungry start-up that must start small and steadily grow even in the face of a skeptical pundit class. Ultimately, our path to victory requires us to tap into grassroots discontent with the current leadership in Washington and the governor's office, and then convert it into a movement for the idea-driven alternative Marco Rubio offers."