Barack Obama has met Pope Francis for the first time, telling him it is a "great honour" to be received by the 77-year-old pontiff at the Vatican.

In their preliminary exchange of pleasantries, the US president said he was the pope's "great admirer", and the pair went on to spend 54 minutes together – an unusually long meeting by papal standards.

The US president was greeted at the Vatican with a display of pomp that was in stark contrast to their expected discussion on how to tackle poverty and inequality.

With his poll ratings under siege, Obama will doubtless be hoping to tap into a little of the Argentinian pontiff's magic. But it remained to be seen how far the pope would push the Vatican's agenda, which includes objections to the US administration's policies on abortion and contraception.

The president swept into the Vatican in a cavalcade of more than 50 vehicles including at least one packed with masked anti-terrorism specialists. Kathleen Hennessey of the Los Angeles Times, who is travelling with Obama, tweeted that his official state car – nicknamed the beast – was too big to get through the gates of the Vatican, and that the president had to enter the courtyard of the Apostolic Palace in a relatively modest black SUV.

Pope Francis gave Obama a restrained smile as they shook hands. Taking his place across from the pontiff in the study where Francis receives his guests, Obama said: "It's wonderful meeting you. I'm a great admirer. Thank you, sir. Thank you."

In case the point had been missed, he added: "It's a great honour. I'm a great admirer. Thank you so much for receiving me."

He said he brought greetings from his family and mentioned that they had met Francis's predecessor, Pope Benedict. The pope's responses could not be heard, but one of those present said that at one point he had answered "thank you" in English.

The doors were then closed so that the two men could continue their discussions in private with just two interpreters: one a pink-sashed monsignor; the other a woman wearing a black lace veil to cover her hair.

The president had earlier lavished praise on Francis, telling the newspaper Corriere della Sera: "The Holy Father has inspired the peoples of the entire world – and me too – with his commitment to social justice and his message of love and compassion, especially for people who are the poorest and most vulnerable among us."

Obama added: "He doesn't just proclaim the gospel. He lives it."

He said: "We know that, given his great moral authority, when the pope speaks his words have an enormous weight."

While skipping a question about their differences over abortion and contraception – "one of the qualities I most admire in the Holy Father is his courage in not mincing his words" – the president tried to keep the focus on their common interest in tackling poverty and hunger.

Thursday's meeting took place as the US administration backed a campaign to raise the federal minimum wage. But it also came just two days after the US supreme court heard arguments in a challenge to Obama's affordable care act, which requires for-profit insurance companies to cover the cost of contraception.

This was Obama's second visit to the Vatican. In 2009, he met Benedict for just under half an hour.