WASHINGTON -- Karl Rove, the cerebral strategist who was instrumental in propelling George W. Bush from Texas to the White House, announced yesterday that he is resigning from the administration position that has made him a magnet for Democratic opponents.
A close adviser who has had Bush's ear for nearly three decades, Rove is more responsible than anyone outside the president's family for Bush's two victories as Texas governor and back-to-back wins in presidential elections, longtime observers say.
Rove is known for mining voter trends and targeting demographic groups, such as religious conservatives and Latinos, displaying a knowledge of policy and history that made him the most influential White House adviser in a generation.
But to detractors, he practiced a divisive brand of electioneering that contributed to the corrosive atmosphere in Washington.
"There would not have been the phenomenon of George Bush had it not been for Karl Rove. It's that simple," said Bill Israel, who taught a University of Texas class on politics and the press with Rove a decade ago and is author of a forthcoming book on the consultant, Stealing Reality.
Rove's record has not been unblemished. He has not, for example, achieved his lofty goal of extending Bush's success to the GOP as a whole, establishing a long-term governing majority.
Presidential candidates running for the Republican nomination next year are distancing themselves from Bush, with none positioning himself as Bush's heir. Democrats gained control of Congress last year, a repudiation of Rove's roadmap.
Inside the White House, Rove, a deputy chief of staff and senior adviser, became Bush's most trusted aide, second only to Vice President Dick Cheney in influence. He played a hand in everything from Bush's push for tax cuts during his first term to this year's ill-fated immigration reform battle. His departure at the end of the month is expected to leave a hole that no one person can fill.
"It's not like there is another Karl Rove out there to step in," said White House deputy press secretary Tony Fratto. "His strategic advice has been invaluable. He has incredible depth of knowledge of policy."
Joshua B. Bolten took on some of Rove's responsibilities when he became Bush's chief of staff last year, and White House counselor Ed Gillespie, a former chairman of the Republican National Committee, can reach out to conservative groups that form Bush's base.
But Rove's real strength was in identifying long-term trends and plotting the future, skills that are of diminished value with just 17 months to go in Bush's presidency.
"He has provided the grand strategy," said George C. Edwards III, a presidential historian at Texas A&M University. "He has found the opportunities, and he has done his best to exploit them."
Rove will become the highest profile aide to leave the administration, which is deep into lame-duck status. His exit will deprive Bush of the ready presence of a trusted friend as the president confronts the burdens of the Iraq war and a Congress controlled by a vocal opposition party.
"I'm grateful to have been a witness to history," Rove said, his voice cracking with emotion as he stood by the president's side on the South Lawn of the White House and made public a decision first disclosed yesterday on the editorial pages of The Wall Street Journal. "It has been the joy and the honor of a lifetime."
Rove, 56, is giving up political consulting and plans to write a book and spend more time with his family, he told reporters. He said he was unlikely to get involved in the 2008 presidential contest.
Bush said that he and Rove began discussing the aide's exit a year ago. The president thanked Rove for the sacrifices made by him and his family.
"We've been friends for a long time, and we're still going to be friends," Bush said. "We worked together so we could be in a position to serve this country."
There was no indication that Bush had asked Rove to leave the administration. Rove had been under fire in recent months from congressional Democrats investigating his role in the firings of several U.S. attorneys, and he received a subpoena to testify. Investigators are seeking thousands of e-mails sent by Rove using an account maintained by the Republican National Committee.
Earlier, Rove's name was linked to a special prosecutor's investigation of the leak of the identity of covert CIA officer Valerie Plame. He was not charged with a crime.
Bush called Rove "the architect" because of the strategist's crafting of a winning formula in the 2000 presidential election.
It was Rove who developed Bush's persona as a "compassionate conservative" and who conceived of attracting votes from the religious right that were critical in both presidential victories, Edwards said.
But for all his innovation, Rove was unable to help the president achieve policy victories on Social Security, immigration and other issues the strategist considered critical for the GOP to cement its long-term majority status.