In a move to thwart an attempt to rewrite the Honduran constitution, soldiers have arrested President Manuel Zelaya in what one leader has called a coup and which the European Union has condemned as unconstitutional.

Just before polls were to open on a controversial referendum to allow the president more than a single four-year term, which had led to escalating political tensions in this Central American nation in recent days, soldiers surrounded the president's home and took him into military custody.

Speaking to a local television station Sunday from the airport in Costa Rica's capital, San Jose, Mr. Zelaya said soldiers arrested him in his pajamas and beat his body guards in what he criticized as "a coup" and "a kidnapping."

Zelaya is an ally of leftist leader Venezuela President Hugo Chávez, who expressed support of his referendum along with Cuba's Fidel Castro. Honduras had joined ALBA, the alliance of leftist leaders in the region as an alternative to free-trade agreements they say are dominated by the US. Across Latin America, leftist leaders have successfully rewritten their constitutions to enable their re-elections. But while Mr. Chávez, Evo Morales in Bolivia, and Rafael Correa in Ecuador have successfully modified their charters to elongate their rule, it seems Zelaya miscalculated his institutional backing.

"Zelaya confused himself with (other) governments by assuming that he had a constituency when he didn't really," says Larry Birns, head of the Council on Hemispheric Affairs in Washington. "He is not a person who had hit a respondent chord in the population, which he could politically rely upon. ... It was a miscalculation."

Spat with the military

Zelaya fired the armed forces Joint Chiefs of Staff, Gen. Romeo Vasquez after his refusal to support an unofficial referendum to modify the nation's constitution, and then refused to back down even after the Supreme Court deemed the referendum illegal and Congress failed to support it. Soldiers, in dozens of white pickup trucks, reportedly put Zelaya in military custody in his home before taking him to an air force base outside the capital city. Neither the military nor presidential advisers have said who is in charge of the government right now.

"We're talking about a coup d'etat," said union leader and Zelaya ally Rafael Alegria. "This is regrettable."

Polarizing drive to rewrite the Constitution

Despite a history of coups, Honduras has been stable since military rule ended in the 80s. But the drive to modify the constitution deeply polarized the country.

The European Union has condemned his overthrow, saying the leader should be returned immediately. In a statement, the 27 ministers of the EU called it an "unacceptable violation of the constitutional order in Honduras."

In a show of support for Zelaya in recent days, Chávez, according to the Miami Herald, said: "there is a coup d'etat under way in Honduras," led by the "retrograde bourgeoisie."

Events in Honduras could have deeper political ramifications. "If he is unseated, this will represent the first political reversal that the ALBA countries have had," says Mr. Birns. "They have scored a noticeable victory with Ecuador, and recent elections in El Salvador. This will mark a reversal of its prospects."