WASHINGTON (AFP) - Karl Rove, the master political strategist behind President George W. Bush's two election triumphs, quit yesterday, paying emotional tribute to the "farsighted courage" of his boss and close friend.
In a bombshell announcement, Rove -- once the hunter, now the hunted as Democrats probe his role in a row over fired federal prosecutors -- said he was stepping down as deputy chief of staff after six tempestuous White House years.
"I'm grateful to have been witness to history," said Rove, revered as a genius by Republicans, and feared as a no-holds-barred opponent by Democrats who repeatedly fell victim to his mastery of US politics.
"I've seen a man of farsighted courage put America on a war footing and protect us against a brutal enemy in a dangerous conflict that will shape this new century," Rove said, as he stood with the president at the White House.
Bush praised Rove, who will leave at the end of the month, for making "enormous sacrifices" to serve, and in a nod to his own waning days in power said: "I will be on the road behind you here in a little bit."
But Democrats, who have repeatedly been victims of Rove's hard knuckle brand of politics, said that Rove had left a stain on Washington.
"Goodbye, good riddance," said Democratic presidential candidate John Edwards in a terse statement.
Another 2008 Democratic hopeful, Senator Barack Obama, was also scathing.
"Karl Rove was an architect of a political strategy that has left the country more divided, the special interests more powerful, and the American people more shut out from their government than any time in memory," Obama said.
Senate Judiciary Committee chairman Patrick Leahy, who has subpoenaed Rove in the row over the firing of prosecutors -- which critics say was for political gain -- accused Rove of manipulating elections and putting himself above the law.
"There is a cloud over this White House, and a gathering storm. A similar cloud envelopes Mr. Rove, even as he leaves the White House," Leahy said.
Rove masterminded Bush victories in two close-fought elections, by appealing to conservatives and disdaining the conventional wisdom that US elections are won from the center.
But he leaves office having failed in his ultimate political ambition of piecing together an enduring conservative ruling majority, after Democrats got their revenge and seized control of Congress last November.
Rove, dubbed by some critics as "Bush's brain" but honored by the president as "the architect" of the 2000 and 2004 election triumphs, had been expected stay on until Bush leaves office in January 2009.
"I've asked a lot of my family, and they've given all I've asked and more," Rove said.
"Now it seems the right time to start thinking about the next chapter in our family's life."
There will now be speculation as to whether he will take a role in any of the 2008 campaigns of Republicans vying to succeed Bush in the White House.
But he told reporters aboard Air Force One en route to Texas on Monday that he would play no official role in 2008, and the Senate subpoena had no influence on his decision to leave.
The timing of Rove's departure means he will absent from the White House's political battle with Congress, expected in September when the top US general and diplomat in Iraq deliver a progress report on Bush's war strategy.
Bush, who once dominated the US political scene, is mired in a prolonged slump: the president's job disapproval ratings stood at a dismal 63 percent at the end of last month, the worst showing since president Jimmy Carter, sending alarm bells through the Republican establishment.