U.S. Vice President JD Vance and Secretary of State Marco Rubio were among the estimated 200,000 people in attendance Sunday to witness Pope Leo XIV's inaugural Mass from St. Peter's Square in Rome.

Leo emphasized a message of unity and a strong rejection of hatred and division. Vance, who converted to Catholicism in 2019, said he was "thrilled" to attend Mass under the first American pope and also extended an invitation for him to visit the U.S.

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"[Leo] and I had a very good conversation with Secretary Rubio this morning," Vance said Monday. "We talked about a number of diplomatic issues and I think the Vatican — particularly the pope — is going to be a great advocate of world peace."

"We're going to find some very important things to work together on," he added.

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Pope Leo, formerly Cardinal Robert Prevost, has a history of being critical on social media of Vance and President Donald Trump in the past. In one post, then-Cardinal Prevost directly fact-checked the vice president on matters of Jesus' teachings.

"JD Vance is wrong: Jesus doesn't ask us to rank our love for others," he wrote.

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Vance, nonetheless, congratulated Leo upon his election as the new leader of the Church.

"I'm sure millions of American Catholics and other Christians will pray for his successful work leading the Church," the vice president said in a statement. "May God bless him!"

Vance also met briefly with the late Pope Francis last month on Easter Sunday, one day before he died at the age of 88.