Callista Gingrich is the president of both Gingrich Productions in Arlington, Va. and the charitable non-profit Gingrich Foundation, and is a former Congressional aide.

She is also a long-time member of the choir at the Basilica of the National Shrine of the Immaculate Conception in Washington, D.C.

Newt and Callista married in 2000, after having a six-year affair while Newt was married to his previous wife. Newt converted to Catholicism in 2009 and explained, in an interview that year with Deal Hudson at InsideCatholic.com, how Callista's witness as a Catholic brought him towards the faith. 

He noted that he had attended Masses at the National Shrine where Callista sang in the choir, and she "created an environment where I could gradually think and evolve on the issue of faith."

At the National Catholic Prayer Breakfast in 2011, he also cited Pope Benedict XVI's 2008 visit to the U.S. as a "moment of confirmation" for him. At vespers with the Pope, where Callista sang in the Shrine choir, Newt recalled thinking that "here is where I belong."

The couple worked on a documentary together that was released in 2010, "Nine Days That Changed the World," that focused on Pope St. John Paul II's 1979 pilgrimage to Poland when the former Soviet bloc country was under a communist government.

The documentary explained how the Pope invigorated the faith of the Polish people in Jesus Christ during his pilgrimage there, and how the visit precipitated the fall of Communism.

In an Easter message posted on the website of Gingrich Productions, the couple noted that "we should remember the many threats facing Christians today," including "a growing secularism, which seeks to place human desires ahead of God and His will," and "radical Islamism" that "seeks to destroy Christianity across the globe."

"But in the face of this evil, we remember the words of Saint John Paul II, who throughout his papacy urged us to, 'Be not afraid'," the statement continued.

As ambassador, Gingrich would follow Ken Hackett, the former head of Catholic Relief Services who served during President Obama's second term as president. 

In a January interview with CNA, Hackett opined that there would be areas of difference and of collaboration between the U.S. and the Holy See under the Trump administration.

One of the possible areas of tension might be on immigration and refugees, as Trump criticized Pope Francis on the campaign trail in 2016 after the Pope said a Mass at the U.S.-Mexico border and urged everyone to pray for conversion of hearts over the suffering of forced migration.

Trump, who repeatedly promised to build a wall on the U.S.-Mexico border and make the Mexican government pay for it, said last February that the Pope was a "pawn" of the Mexican government and "is a very political person, I think he doesn't understand the problems our country has."

He also issued an executive order shutting down refugee admissions for four months at a time when Pope Francis has taken in refugees and U.S. bishops have called for the country to continue accepting refugees fleeing violence.

Meanwhile, there are other possible areas of collaboration between the U.S. and the Holy See, Hackett said in January, including on human trafficking, peace in the Middle East, a solution to the worsening crisis in Venezuela, and efforts to alleviate global poverty.

President Trump and Pope Francis will meet at the Vatican on May 24.