Before Mr Rudy Giuliani became a contender to be the US' top diplomat, the 72-year-old was ironically best known for his distinctively undiplomatic style.
He shot to national fame for his hardline crackdown on crime in New York City when he was elected its mayor in 1994. He became an international figure seven years later for his leadership during the Sept 11, 2001 terrorist attacks.
His handling of the aftermath of the attacks led him to being dubbed "America's mayor" and he received an honorary knighthood from Queen Elizabeth in 2002.
Time magazine named him its Person of the Year in 2001. In its citation, Time noted how Mr Giuliani had stepped up on the day of the attack at a time when then President George W. Bush was out of sight.
"Giuliani became the voice of America. Every time he spoke, millions of people felt a little better. His words were full of grief and iron, inspiring New York to inspire the nation."
In the years since, however, Mr Giuliani has turned into a far more divisive figure.
On the campaign trail, he proved to be one of Mr Trump's most vocal supporters, and seemed to relish making controversial statements.
He was also the highest-profile Trump surrogate to push theories that Mrs Hillary Clinton, Mr Trump's opponent for the presidency, was covering up a major illness.
A year earlier, he made headlines when he accused President Barack Obama of not loving his country. "He wasn't brought up the way you were brought up and I was brought up through love of this country," he had said in a speech.
As for foreign policy experience, Mr Giuliani's experience primarily comes from his work consulting with foreign governments and businesses - though his clients have also been controversial.
In 2011, for instance, an Iranian political group known as the Mujahedin el-Khalq paid the former New York City mayor to give a speech urging the US State Department to remove the group from its list of terror organisations.
Then there are concerns over his temperament for the job. One particular incident stands out. In 1995, he started an international incident by removing Palestinian leader Yasser Arafat from a UN gala in New York, prompting widespread condemnation.
The New York Daily News quoted Mr James Zogby, president of the Arab-American Institute, as saying: "At best I can describe, it is uncivil behaviour, and at worst it's a disgusting display of a lack of diplomacy on the part of the mayor."
Jeremy Au Yong
