Washington  - George W Bush leaves office with job approval ratings at historic lows of below 30 per cent, still high compared to his popularity in most other countries.

With unfinished wars in Afghanistan and Iraq, terrorist leader Osama bin Laden still on the loose more than seven years after 9/11, and the US economy in its worst tailspin in decades, critics at home and abroad have often wondered how he could have been elected twice.

On the eve of the November 7, 2000, elections, which he would win after an extended court challenge, Bush explained his first victory at a campaign stop in Arkansas, coining a term: "They misunderestimated me."

It would not be the last time that Bush's opponents misunderestimated him, nor would it be his last use of the nonsensical word.

His tendency for verbal trips and other gaffes spawned a cottage industry that must now be contracting with the rest of the economy. US journalist Jacob Weisberg's Bushism book series became an international best-seller.

Often painted as an ignoramus, Bush holds degrees from the two most prestigious universities in the United States: a bachelor's from Yale and a master's in business administration from Harvard.

Education, though, has been a mother lode of irony for Bush. Long before terrorism and Iraq were on his radar screen, raising school standards was a pillar of his first presidential run. Campaigning in early 2000 for the South Carolina Republican primary, he emphasized that society must ask: "Is (sic) our children learning?"

Congress passed his No Child Left Behind Act during Bush's first six months in office, forcing public schools to measure student performance and show continual improvement. Critics have complained about the burden on schools and the classroom distraction of excessive standardized tests.

Defending his domestic policy legacy, Bush confronted the issue in 2007, after a report of rising national test scores. "As yesterday's positive report card shows, childrens
(sic) do learn when standards are high and results are measured," he said.

Bush has a way of turning old sayings inside out.

In 2002, he attended an event in Tennessee to promote patriotic education, only to get off on a tangent about Saddam Hussein's refusal to cooperate with UN weapons inspections: "Fool me once, shame on - shame on you. Fool me - you can't get fooled again."

In 2004, in the midst of his successful re-election bid, Bush was expounding on the merits of some defence legislation.

"Our enemies are innovative and resourceful, and so are we," he said. "They never stop thinking about new ways to harm our country and our people, and neither do we."

He mangled the language with real creativity. In 2006, he declared himself "the decider," and later that year told CNBC that he liked using "the Google" to look at satellite images of his Texas ranch. During his re-election campaign, Bush tried to dispel "rumours on the internets" about a military draft.

Bush's foreign misadventures were personal as well as policy- based.

At the 2007 Asia-Pacific Economic Cooperation meeting in Sydney, Bush called it an "OPEC summit," instead of APEC, and later described how Australian Prime Minister John Howard had visited "Austrian troops."

At the end of the summit, posing in front of the iconic Sydney Opera House for a group photo, all in matching Outback oilskin jackets, 20 leaders all waved their right hands as asked. Standing on one end, Bush waved his left.

Whatever history's judgement of his legacy, Bush has often displayed a healthy sense of humour. At the 2004 Republican convention, he admitted "a few flaws."

"People sometimes have to correct my English," he said. "I knew I had a problem when Arnold Schwarzenegger started doing it."

But naturalized citizens, like the Austrian-born California governor, are ineligible to become president. With Bush leaving office on January 20, who will carry on his verbal legacy?

President-elect Barack Obama is a smooth talker who has carefully avoided putting his foot in his mouth. That job might be filled by Joe Biden, whose only constitutional duty as incoming vice president is to break tie votes in the US Senate.

September's financial meltdown on Wall Street evoked frequent references to the 1929 stock market crash. In an interview in the midst of the burgeoning crisis, Biden gave broadcaster CNBC his own, flamboyantly errant version of history: "When the stock market crashed, Franklin D Roosevelt got on the television."

FDR, whose fire-side radio chats soothed the nation during the Great Depression, was only elected president in 1932, and Roosevelt would become the first president on television only in 1939.

For Biden, who has a long history of controversial statements and even plagiarism incidents, it was a good start. (dpa)