Karl Rove, President Bush’s close friend and chief political strategist, announced Monday he will leave the White House at the end of August, joining a lengthening line of senior officials heading for the exits in the final 1 1/2 years of the administration.

On board with Bush since the beginning of his political career in Texas, Rove was nicknamed “the architect” and “boy genius” by the president for designing the strategy that twice won him the White House. Critics call Rove “Bush’s brain.”