By Jonathan Beale
BBC News, Washington
Gift shops have long been preparing for the Pope's visit
President Bush is not a Catholic. And unlike his good friend Tony Blair, he probably never will be.
Yet the very Protestant Mr Bush is clearly an admirer of Pope Benedict XVI and is pulling out all the stops for his first visit to the United States as pontiff.
For a start, the president and his wife Laura are making the rare gesture of going to meet Pope Benedict at Andrew's Air Force Base when he lands on Tuesday evening.
Normally world leaders and heads of state have to make the journey to the White House to see Mr Bush.
Not that they see eye-to-eye on every issue.
This Pope has criticised the war in Iraq - highlighting the suffering of Iraq's Christians. But on issues like the sanctity of life, human rights and the freedom to worship, the president and the Pope share a common agenda.
In fact some have even described President Bush as a "closet Catholic".
The former Republican Senator, Rick Santorum, calls him "the first Catholic president... much more Catholic than Kennedy", who found his faith in the 1960s as much a burden as a blessing.
This visit, though, is about much more than seeing the president.
In fact, Pope Benedict will not even turn up to the White House dinner being held in his honour and marking his 81st birthday.
Catholics are keenly anticipating the Pope, but he may have broader appeal
Instead, he will be meeting Catholic bishops for prayer.
On his six-day tour Pope Benedict will also hold a Mass for the faithful at baseball stadiums in Washington DC and New York.
Some 46,000 American Catholics are expected to attend the service at the new Nationals Park stadium in DC, while 50,000 are due at the Yankee Stadium in New York.
It is a reminder that although the United States is not a Catholic nation, it does have the world's third largest number of Catholics - after Brazil and Mexico.
There are 70 million Catholics in the United States - a quarter of the country's adult population.
While in New York, Pope Benedict will also be addressing a global audience when he speaks at the headquarters of the United Nations.
So this is an important visit for a Pope who is still to make his mark in the same way as his predecessor - the much-loved and more charismatic John Paul II.
This Pope remains unfamiliar to most Americans. A recent survey by the Pew Forum on Religion and Public Life found that three in 10 people did not know enough about him to give an opinion about his leadership of the Catholic Church.
Rift with liberals
One of the biggest tests for Pope Benedict is how he heals the wounds of the sex abuse scandal that rocked the American Catholic Church in 2002.
Hundreds of priests have since been removed, and the Church has spent $2bn (£1bn) in payouts following legal claims from an estimated 5,000 victims.
Washington's new baseball stadium, Nationals Park, will host a Mass
The Pope is expected to address the matter, but at the time of writing there were no plans for him to meet any of the victims - as some have urged. It is clearly not an issue on which the Catholic Church wants to dwell.
This Pope may also be at odds with liberal Catholics in America. Not all subscribe to his orthodox position on contraception, abortion or same-sex relationships.
Some 62% of Catholics in America say the Pope is out of touch with their views.
Yet at the same time there is a growing Latino population who look to the Pope as the true leader of their faith.
An even greater number of evangelical Christians in America share the Pope's concerns about rapid changes in society and proclaim a similar gospel.
In fact, overall, Pope Benedict may find that more Americans are in tune with his thinking than in more liberal Europe, where the band of believers is dwindling.
In America, 40% of Catholics still go to Mass, compared with around 10% in Europe.