"The President looks forward to discussing with Pope Francis their shared commitment to fighting poverty and growing inequality," the White House said in a statement. Politicians across the political spectrum - from Rep. Paul Ryan (R-Wis.) to Senate Majority Leader Harry M. Reid (D-Nev.) - have sought to associate themselves with Francis's populist rhetoric about the need to challenge the "idolatry of money" and address the needs of the poor. A trip to the Vatican gives the president a chance to frame one of his signature domestic issues in largely moral terms. But the journey also highlights the continuing disagreements between the Obama administration and the Catholic Church over issues such as abortion rights and same-sex marriage. Sen. Bernard Sanders (I-Vt.) said in an interview Tuesday that the Vatican meeting is significant because Francis has made "wealth and income inequality a moral issue." "Clearly, the pope and the president have their differences," but widening inequality clearly troubles both of them, Sanders said. It is a moral issue, and once we begin to look at those issues from a moral perspective, it demands political solutions. Obama has gone out of his way to praise the pope in recent months. In an interview last month on MSNBC's "Hardball," the president described Francis as an "extraordinarily thoughtful and soulful messenger of peace and justice." "I haven't had a chance to meet him yet," Obama said. But everything that I've read, everything that I've seen from him, indicates the degree to, to which he is trying to remind us of those core obligations. But some Catholic conservatives note that Obama and Francis diverge in key respects. "I think the difference between Pope Francis and President Obama on the question of poverty is one of emphasis," Andrew V. Abela, Catholic University's business and economics dean, wrote in an e-mail. The President is policy driven, while the Pope, by contrast, sees poverty not as a technical problem - for him it is a human, relational problem. At the root of the Pope's vision is personal relationship. He is fighting against a culture of exclusion; poverty, for him, goes way beyond a question of insufficient income: it means being left out of the human family," Abela continued. I think that the real opportunity here is for the pope's call to each one of us to care for the poorest among us to be heard and acted upon. I think it diminishes this call to reduce it to a policy debate. Miami Archbishop Thomas Wenski, who chairs the committee on domestic social development for the U.S. Conference of Catholic Bishops, said in an interview that several of Obama's policies are at odds with those of the church, including his opposition to using taxpayer funds to finance vouchers in the District of Columbia so parents can spend them on tuition at Catholic schools. "If Obama would see our way with the voucher system, we could help get a lot of kids out of poverty by giving them the tools to have a successful life through Catholic schools," Wenski said. Still, Francis may be uniquely positioned at this moment to amplify Obama's economic message. A Quinnipiac University poll found that 68 percent of Catholic voters agreed with the pope's remarks that the church has become too focused on issues such as homosexuality, abortion and contraceptives. And his popularity is not limited to Catholics. A December Washington Post-ABC News poll found that 92 percent of Catholics and 62 percent of non-Catholics had a favorable view of him. "Like every other person on the planet, President Obama would like to be seen in a picture with Pope Francis at this point," said Stephen Schneck, who directs the Institute for Policy Research & Catholic Studies at Catholic University and served as national co-chair of Catholics for Obama. The fact that Pope Francis has moved the issue of "poverty to the top of his agenda," Schneck said, makes a discussion of economic inequality "a particularly good fit at the moment." Peter Wehner, who directed the White House Office of Strategic Initiatives in the George W. Bush administration, said a papal visit "elevates the president out of the day-to-day nastiness of politics and puts the nice frame around" an issue he cares about. "The American people like to see their president in those types of meetings with those kinds of moral figures," said Wehner, a senior fellow at the Ethics and Public Policy Center. I'm not sure it changes any votes. Wehner said such meetings raise the risk that those around the pope will air their differences on issues such as abortion. Wenski said the Catholic leader is likely to bring up the church's objections to contraception coverage requirements under the Affordable Care Act. The issue came up during Secretary of State John F. Kerry's visit to the Vatican this month. Noting that the late John Paul II had clashed with President George W. Bush on whether to invade Iraq, Wenski said that presidents and popes have long had their differences but still found good reasons to meet. "We know there's a political calculation in this," he said, "but Pope Francis, and popes in general, are not usually naifs." Michelle Boorstein and Scott Clement contributed to this report.