George W. Bush says he will be long gone when posterity delivers a final verdict on his tumultuous presidency.

But he will give history a shove in Dallas on Thursday when he opens his presidential library, showcasing his self-image as a leader of a land under attack who made tough decisions that kept Americans alive.

From a steel beam twisted in the inferno of the World Trade Center, to footage of the twin towers collapsing in ash clouds, the September 11 attacks loom large over the museum of Bush's 2001-2009 administration.

Visitors will find an apt proxy for the man himself: the museum at Southern Methodist University pulses with energy and patriotism but Bush skeptics may find a lack of nuance and absence of self doubt.

Bush has chosen to ask a direct question of the tourists and historians of tomorrow: 'what would you have done in my shoes on terrorism and Iraq, Hurricane Katrina and the 2008 economic crash?'

The airy limestone building will be dedicated with President Barack Obama and all living ex-US presidents on hand.

Dignitaries will enter a "Freedom Hall" before viewing exhibits detailing Bush policy on issues like education and tax cuts.

But suddenly, they will turn a corner to confront a chunk of wreckage from Ground Zero and walls bearing names of 9/11 victims.

The story is of a president who thought he was going be occupied with domestic policy only to find himself defending the homeland from Al-Qaeda.

Bush wrote in his 2010 memoir that "it's too early to say how most of my decisions will turn out."

"Whatever the verdict on my presidency, I'm comfortable with the fact that I won't be around to hear it."

But he left office in 2009 as one of the most unpopular presidents in recent history, with a Gallup approval rating of just 34 percent.

Scholars polled by Siena College in 2010 put Bush in the bottom five of all US leaders.

His absence from the scene seems to have improved his image slightly: in a CNN/ORC poll Wednesday, 42 percent said Bush's presidency was a success.

But critics say Bush invaded Iraq on false pretenses, mismanaged the occupation and thereby weakened America's global power and moral standing.

The aftermath of Katrina in 2005 remains a masterclass in how not to handle natural disasters.

And Bush's failure to spot an onrushing financial meltdown led to the greatest recession since the 1930s.

Yet, former Bush aides hope the opening of the library will mark the first step in a reappraisal.

They look to presidents Harry Truman and Dwight Eisenhower, who limped out the White House but were later rehabilitated by history.

"Those eight years of the Bush presidency were full of shocks," said Karen Hughes, one of Bush's most trusted senior aides.

"As time passes, as emotions begin to even out after a very difficult and consequential time, people take a much more objective look."

However, Professor Bruce Buchanan, a presidential scholar at the University of Texas, said Bush's reputation is out of his hands.

Transformations "haven't occurred after an effective PR effort by a president or his supporters," he said.

Only if new information sheds a fresh light on his administration, or a future biographer can reshape his image, will Bush's stock rise, he said.

"Iraq is what would have to be reinterpreted" said Buchanan, but there are few signs the country will become the democratic paragon Bush promised.

The centerpiece of the Bush library is an interactive exhibit known as "Decision Points Theater."

Bombarded by footage of breaking news, and offered short videos of "advice" from actors posing as officials and military top brass, visitors use touch screens to make their own decisions on the crises that defined Bush.

The ex-president then pops up on a screen to justify the real steps he took on four key issues, the invasion of Iraq and the subsequent troop surge, Katrina and the financial crisis.

"The idea was to show people what it is like to have to make decisions quickly with the press sort of hounding you on when you are going to decide and what are you going to do," said former first lady Laura Bush.

The museum, which includes a stunningly accurate replica of Bush's Oval Office, also highlights the Bush doctrine" of pre-emptive war born after the September 11 attacks.

"Take the fight to the enemy ... confront threats before they fully emerge," reads one blunt display.

Like their boss, Bush veterans seem at peace with their actions -- for instance harsh interrogations of terror suspects that critics deemed torture.

"I know it prevented acts that saved American lives. I know it allowed us to get inside (Al-Qaeda)," former national security advisor Stephen Hadley told AFP.

"I think (Bush) made the right call and there are Americans alive today that can thank him for it."