Donald Trump’s second term could lead to a shake-up of US diplomacy which moves it more toward populist, authoritarian leaders, political observers have said.

Nearly half of US voters told an AP VoteCast survey they were “very concerned” that another Trump presidency would bring the country closer to authoritarianism.

Hungary – Prime Minister Viktor Orban

Viktor Orban is Trump’s biggest cheerleader in Europe.

Regarded with suspicion by the rest of the EU because of his ties to Vladimir Putin, the Hungarian leader celebrated Trump’s victory and the pair have already spoken over the phone.

Orban has been accused by the EU of burying Hungary’s democracy by dominating media and building a network of loyal oligarchs.

His government has also come under fire for its record on political freedom, women’s equality and LGBT rights.

Russia – President Vladimir Putin

Trump has avoided publicly criticising Putin and has sometimes spoken warmly about him, in contrast to most Western leaders.

He once called the Russian president “genius” and “savvy” for his campaign against Ukraine – though he later publicly condemned the invasion.

Trump has also claimed he would end the war in Ukraine “within 24 hours” if re-elected – a vow welcomed by the Kremlin, which currently holds an advantage on the battlefield and about a fifth of Ukrainian territory.

Nigel Gould-Davies, of the International Institute of Strategic Studies, said “there is clearly that sort of authoritarian-minded chemistry,” between the two leaders.

He said Putin and other authoritarian leaders will be pleased about Trump’s re-election, which will mean “much less emphasis in American foreign policy on the importance and value of human rights”.

India – Prime Minister Narendra Modi

Narendra Modi sent the “heartiest of congratulations” to his “friend” Donald Trump after it was announced he would return to the White House.

Modi is a popular but polarising leader whose politics have divided India, especially along religious lines.

He has presided over a fast-growing economy while advancing Hindu nationalism in his country.

Modi has been accused of using hate speech against the country’s minority Muslim community, especially in the last phase of election campaigning this year.

His supporters think he has improved India’s standing in the world, but his critics say he has eroded the country’s democracy.

Turkey – President Recep Tayyip Erdogan

Recep Tayyip Erdogan hailed Trump’s win as a “new era” for America after a “great battle” by the president-elect.

Like Trump, Erdogan projects an image of strength that prioritises national interests and relies on messages that present him as a leader for the people.

The US has been intent on keeping Turkey at arms-length due to its stance on a range of issues, most recently its support for Hamas in the Gaza war.

However, Trump and Erdogan have cultivated a cordial relationship despite a series of differences between their countries.