COLUMBIA, S.C. — The campaign chief and deputy campaign manager for Republican presidential contender Michele Bachmann are leaving in a campaign shake-up.

Bachmann campaign manager Ed Rollins said at 68 he just doesn’t have the stamina for 12- and 14-hour days every day of the week. He said he had planned a transition after putting into place a campaign team and getting past the Iowa Straw Poll. He plans to continue as a senior adviser.

Rollins said his deputy and longtime colleague, David Polyansky, decided that it was a good time for him to leave the campaign as well.

Rollins said Texas Gov. Rick Perry changed the dynamic when he joined the field. He said the race is between Perry and former Massachusetts Gov. Mitt Romney, with Bachmann as No. 3.