That's according to Time Magazine, which quotes sources close to Powell as saying that he has a firm plan for an exit after serving out the entire term.
"He will have done a yeoman's job of contributing over the four year," a close aide was quoted as saying. "but that's enough."
The aide stressed that Powell was determined to serve out the entire term, even if the United States launches an invasion of Iraq, which Powell has fought to delay or derail.
If President Bush wins a second term, only the imminence of a major diplomatic victory - in the Middle East, for example - could induce Powell to stay on the job a short while longer, the magazine said.
In an interview with BBC television scheduled for broadcast on Sept. 8, Powell struck a moderate tone in the debate over whether to invade Iraq, insisting that the return of weapons inspectors to Baghdad is a priority.
Until an excerpt from the interview was released on Sunday, Powell had been a silent voice in the public debate. A senior State Department official said on Friday the secretary, seen as the leading dove in an administration dominated by hawks, is keeping his powder dry until President Bush decides how he intends to convert his policy of "regime change" into a plan of action.