By Krisztina Than
BUDAPEST (Reuters) - Hungary's President Janos Ader said on Wednesday he would sign a bill changing the constitution, despite warnings from the European Union, the U.S. government and human rights groups that the legislation could undermine democracy.
Parliament, dominated by Prime Minister Viktor Orban's Fidesz party, voted on Monday for the amendments, which Brussels sees as the latest move to assert power over other branches of the state by Orban, who took power in 2010 with a two-thirds majority in parliament.
The changes include allowing the constitutional court to challenge laws only on procedural grounds, not on their substance, and scrapping all decisions made by the court before 2012, discarding a body of case law often used as reference.
In a statement posted on his official website, Ader, an ally of Orban, said signing the bill was his constitutional obligation, as the document stipulates the president must sign the constitution or amendments within five days of receipt.
"This is my only constitutional choice, which is in line with my oath, the current regulations, and the rulings of the Constitutional Court passed in the past 20 years," Ader said.
"Being a democrat means sticking with the forms and framework of a legal state under all circumstances," he added.
On Monday, thousands of Hungarians protested near Ader's office, demanding he veto the bill.
Opponents of the changes - including former President Laszlo Solyom, who is also a former head of the top constitutional court - cited a clause in the constitution which says the president's most important task is to be a guardian over the democratic operation of the state.
Orban's government says it has the right to use its parliamentary mandate to reform a constitution it calls a hangover from communist rule, and has denied infringing on democracy.
In the past three years Orban has pushed through changes that opponents said could undermine the independence of the media, central bank, judiciary and other institutions.
(Reporting by Krisztina Than; Editing by Michael Roddy)