A battle has erupted in Donald Trump';s camp over his selection of Mitt Romney as US Secretary of State, as loyal supporters are seeking to block the appointment of the man who was a fierce critic of the President-elect during the 2016 presidential campaign.

The debate over selection of  US Secretary of State has led to an internal dispute in Trump’s team between supporters of Romney, those favouring former New York City Mayor Rudy Giuliani and others who believe Trump should keep searching for candidates.

Although, Romney, who was nominated by the Republican Party in 2012 to be US president, is the leading prospect to become America's top diplomat in Trump’s incoming administration. Some of Trump';s loyalists however, have united to oppose the appointment of Romney, who called the celebrity businessman a "fraud" and a "conman" during the presidential campaign.

The former Speaker of the House of Representatives, Newt Gingrich, who was also one of the 2012 Republican presidential candidates in a FOX News interview, expressed scepticism that Romney would represent "the kind of tough-minded, America-first policies that Trump has campaigned on,” saying "I can think of 20 other people who would be more naturally compatible with the Trump vision of foreign policy."

In that same interview, the former Governor of Arkansas and one of the 2016 presidential candidates, Mike Huckabee, told Fox News that he is "still very unhappy that Mitt did everything he could to derail Donald Trump."

However, the other leading choice for secretary of state, Giuliani, has made some US diplomats and ethics experts wary because of his business dealings with foreign governments, as well as his lack of experience in foreign policy.

Giuliani, who has been one of Trump';s staunchest supporters from early in his campaign, has openly lobbied for secretary of state, telling Trump';s advisers he is interested in no other position, the New York Times reported.

Trump has so far nominated mainly older white men to his future cabinet. His cabinet appointments have signalled his intention to deliver on his hard-line campaign promises and deepened concerns among Muslim Americans about an anti-Islamic White House.

American civil rights organizations and Muslim leaders say they were disturbed by Trump’s national security picks noted for harshly anti-Muslim rhetoric.

Some current and former US government officials are also concerned that Trump’s appointments could reinforce perceptions among Muslims that Washington is at war against the Islamic religion.