Pope Francis and President Barack Obama are set to meet in the Oval Office of the White House on his historic maiden visit to the United States.

The pontiff, who played a crucial role in brokering talks between Havana and Washington, was due to deliver his opening remarks to the US on Wednesday morning on the White House lawn, the first stop on the pope's six-day visit to the country.

"The goal of this meeting is to give the two men the opportunity to talk about their shared values," said White House spokesman Josh Earnest.

"There'll be time for politics, frankly, the other 364 days of the year," he said.

"At least, for that one meeting, it will be an opportunity for the president to put politics aside and have an opportunity to talk about the values that he and the pope have in common."

Later in the day, the pope will meet the country's 450-strong bishops' conference at the Cathedral of St Matthew the Apostle.

Many of the bishops have struggled to come to terms with the pope's new, social justice-minded direction of the church.

They prioritised drawing clearer boundaries for Catholic behaviours and beliefs in the face of legalised abortion, advances in gay rights, and the exodus of many Westerners from organised religion.

The US church spends hundreds of millions of dollars each year through its social service agencies, and for years has sought an overhaul of the immigration system to reunite families, shelter refugees, and give the poor the chance at a better life.

But the US Conference of Catholic Bishops has increasingly put its resources behind high-profile fights over abortion, contraception, and gay marriage.

On Wednesday, the pope will also canonise a Spanish friar who brought the Catholic faith to California.

Francis is to celebrate the mass for the canonisation for Junipero Serra in Spanish. Several thousand of the 25,000 tickets to the event were set aside for Spanish-speaking people, many from California.

The Basilica of the National Shrine of the Immaculate Conception erected a temporary sanctuary on the east portico for the mass.

Source: AP And AFP