Miers, who currently serves as White House Counsel, was nominated Oct. 3 to replace the retiring Sandra Day O'Connor as associate justice of the Supreme Court.
Time Magazine reports Miers, a longtime personal friend and attorney for Bush, was part of his "100-degree club" -- a small group of people who run with the president at his Crawford, Texas, ranch in 100 degree temperatures.
Miers also spent time clearing brush on the ranch.
Bush's senior adviser, Karl Rove, reportedly didn't play a major role in the decision to nominate Miers.
Chief of Staff Andrew Card was the lead adviser in the process, Time said.
An unnamed presidential adviser familiar with the Miers decision said the move appealed to Bush because she is a personal friend of his.
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