Rove was a key force in both of Bush's campaigns for president and, after the 2004 election, was made a deputy chief of staff for policy.
The Washington Post said Rove will be working on the elections next November. Democrats believe the current unpopularity of Bush makes it possible for the minority party to take control of Congress.
Bush and Rove have worked together since the president's run for governor in Texas.
The change was seen as part of the White House realignment set up by the change to Josh Bolten as chief of staff. Bolten took over the position last Friday.
The Post said Rove's White House position is likely to be taken by Joel Kaplan, currently deputy White house budget director.