By the BBC's Robert Plummer Americas Regional Editor

Security has been stepped up outside the parliament of Trinidad and Tobago in preparation for moves to break the deadlock that has paralysed the country's political system for nearly four months.

Parliament, in the capital Port-of-Spain, has not met since the general election last December that ended in a tie between the two main political parties.

Manning became prime minister in December

Talks to resolve the dispute broke down and now the Prime Minister, Patrick Manning, has decided to force a showdown by calling on parliament to elect a Speaker.

However, the opposition leader, Basdeo Panday, who was replaced as prime minister by Mr Manning in December, has refused to co-operate.

The political deadlock reflects bitter rivalry between the two main political parties, in a country where voters' loyalties are largely determined by ethnic origin.

Deadlock

Until last December, the governing party was the United National Congress, which draws most of its support from people of Indian descent.

After the election, it ended up with 18 seats in parliament - as did the People's National Movement, which is supported mainly by Afro-Trinidadians.

President Arthur Robinson tried to resolve the stalemate by deciding on a change of prime minister, and the PNM leader, Patrick Manning, was sworn in on Christmas Eve.

However, Mr Panday - the UNC leader - thought he should have remained in office and he says the only way to settle the matter is for the country to hold its third general election in three years.

President Arthur Robinson tried to break the stalemate

To this end, he has launched what he calls a campaign of civil disobedience.

He compares his struggle to the non-violent protest movements of Martin Luther King and Mahatma Gandhi.

Time, however, is on Mr Panday's side.

Parliament has to convene no later than six months after its last sitting or else fresh elections must be held, and the deadline is next Tuesday.

Mr Panday thinks his party can use filibustering tactics to drag out the session and prevent the election of a new Speaker before then.

But Mr Manning says that it is enough merely to open proceedings, Speaker or no Speaker.

It all hinges on how you interpret the constitution - and in the end, it could be lawyers rather than politicians who decide the future government.