A Republican senator has backed Donald Trump to become the next pope.

Lindsey Graham, the South Carolina senator, urged the papal conclave to “keep an open mind” about Mr Trump when it gathers to select the next head of the Roman Catholic Church next month.

Mr Graham, a frequent golf partner of the US president, said in a tongue-in-cheek X post that he was “excited” about the idea but conceded Mr Trump would be a “dark horse candidate”.

On Tuesday, Mr Trump, marking his first 100 days in office, joked that he would like to become the next pontiff following the death of Pope Francis earlier this month.

“I was excited to hear that President Trump is open to the idea of being the next pope,” Mr Graham responded on social media.

“This would truly be a dark horse candidate, but I would ask the papal conclave and Catholic faithful to keep an open mind about this possibility.

“The first Pope-US president combination has many upsides. Watching for white smoke…. Trump MMXXVIII!” he added, using the Roman numerals for 2028, a rallying call among the president’s diehard supporters for him to seek a third term.

Mr Trump recently endorsed Mr Graham’s re-election bid for next year, praising him as a “wonderful friend” and telling supporters: “He will not let you down.”

On Tuesday, the US president jokingly told reporters: “I’d like to be pope… That’d be my number one choice.”

He went on to say he did not have a preference for Pope Francis’s successor, but added that “we have a cardinal that happens to be out of a place called New York who is very good”, referring to Timothy Dolan, the Archbishop of New York.

Cardinal Dolan, 75, who recently called for the Church to return to its conservative traditions, is not thought to be among the front runners for the position.

The papal conclave will gather on May 7 to elect the Church’s new spiritual leader in the Sistine Chapel.