Hungary's new prime minister has said the government will amend the constitution to remove President Tamás Sulyok after he refused to stand down.

Péter Magyar pledged to remove Sulyok and other key figures appointed by his predecessor Viktor Orbán after his landslide election win in April. 

Magyar has accused the president of serving Orbán's interests and has repeatedly called on him to quit, most recently setting a deadline of 31 May.

Sulyok, who was installed in February 2024 by Orbán's party without a direct election, has refused to resign, saying he intends to serve out his five-year term.

The stand-off leaves the new government facing a constitutional clash with a remnant of the previous regime. 

Orbán's Fidesz party has called Magyar's demand an "unlawful ultimatum".

In a post on X on Sunday, Magyar said: "Tamás Sulyok has never stood up for the vulnerable, for those under attack, or for the rule of law."

He previously said Sulyok was "unworthy of representing the unity of the Hungarian nation" following the seismic political shift which April's election produced, and promised to remove him immediately after his victory.

Magyar's Tisza party won a two-thirds majority in the National Assembly, which gives it the power to amend the constitution, a crucial mechanism the new government will need to unpick Orbán-era reforms. 

Magyar told reporters the process to remove Sulyok would take around a month.

The president again refused to step down on Monday after meeting Magyar, saying "the constitutional crisis situation emerging as a result deepens the social divisions and damages the international judgement of Hungarian democracy".

He claimed the stand-off could threaten the unlocking of EU funds bound for Hungary, the bulk of which were held back due to democratic backsliding under Orbán.

Last week, the EU said reforms spearheaded by the new government could soon see €16.4bn (£14.2bn) in funding handed to Budapest. 

While the presidential role is largely ceremonial under Hungary's system of government, it has some practical functions, including confirming public appointments. On Monday, Sulyok announced several military appointments via Facebook. 

The president can refer laws back to parliament for reconsideration or forward legislation to the constitutional court, which could potentially slow down or block any reform agenda. 

Sulyok was installed as president in February 2024, following the resignation of Katalin Novák over the government's response to a child sex abuse scandal. 

Following the end of his 16-year rule, Orbán stepped down as a member of parliament in April.

Magyar's party has moved to cut off any route back to power by proposing a constitutional amendment limiting any prime minister to eight years in power.