The commission said that it “remains preoccupied that a number of the new provisions may violate E.U. law” and that it “reserves the right to take any steps that it deems appropriate, namely the possibility of launching infringement procedures” — a European Union term for a formal lawsuit. The commission said it planned to complete a full legal analysis of the Hungarian laws within days and make a decision Tuesday on whether to start a process that could eventually lead to a lawsuit.

Foreign critics as well as protesters in Hungary accuse Mr. Orban of pursuing a policy of creeping authoritarianism, using his overwhelming majority in Parliament to make sweeping changes and curtail freedom of the press and the judiciary. Of particular concern to Brussels are the independence of the national central bank, and mandatory early retirement rules that allow the government to force out judges and prosecutors and appoint its own candidates to the positions. Brussels has also expressed concern about the independence of the national data protection authority.

Hungary, which has a long history of excessive budget deficits, technically kept its budget shortfall below 3 percent of gross domestic product last year, in line with European Union rules. But the European Commission said that the result was achieved by one-time factors and that the sustainability of the budget underwent a “severe deterioration” last year, suggesting that higher deficits were likely in the future. Hungary took “no effective action” to rein in its deficit, the commission said.

European officials had hoped that the prospect of losing sorely needed financial assistance from the union and the I.M.F. to shore up the economy would have led Mr. Orban and his government to back down by now, at least on the measures concerning the central bank.

Instead, the standoff has continued, prompting the warning from the commission Wednesday that it is prepared to take Hungary to court to reverse what critics fear is a slow return to the heavy-handed state that prevailed before the fall of Communism more than two decades ago.

“The commission recalls that a legally stable environment, based on the rule of law, including respect for media freedom, democratic principles and fundamental rights, is also the best guarantee for citizens’ trust and confidence of partners and investors,” it said. “This is particularly vital in times of economic crisis. The swiftest way to lay to rest the concerns mentioned would of course be action by the Hungarian authorities themselves.”

A formal European case could take months.

Viviane Reding, the European Union commissioner for justice, suggested Wednesday that Mr. Orban was abusing his parliamentary majority to reshape the Hungarian Constitution for the benefit of his Fidesz Party, rather than for the benefit of the country.