Prague  - Czech lawmakers convened Tuesday to submit Prime Minister Mirek Topolanek's government to a confidence test, the outcome of which could undermine country's presidency of the European Union and efforts to ratify the bloc's reform Lisbon Treaty.

If the government falls, it would also complicate the Czech Republic's efforts to battle the economic slump and deal a major blow to Czech-US missile defence treaties, Topolanek's key foreign policy project.

A lengthy debate in parliament's lower house has been dragging out the vote of no-confidence, initiated by opposition Social Democrats.

The cabinet, which breezed through four such motions in two years in power, has never been closer to losing.

Its fate hangs on a handful of independent lawmakers, who had earlier defected from Topolanek's coalition.

The centre-right three-party cabinet controls 96 votes in the 200- seat lower house, while the leftist opposition commands 97 votes. For the cabinet to fall, the opposition needs an another another four.

In the chamber on Tuesday, the premier called on lawmakers to act responsibly at a time of economic downturn.

"He who votes for the fall of the government is voting for instability, uncertainty and a deepening of the impact of the crisis," he said.

Were the cabinet to collapse, President Vaclav Klaus would hold the key to future developments. He has so far declined to disclose his steps. Meanwhile, Topolanek's cabinet would govern in a caretaker capacity.

Topolanek said Monday that his party would prefer an early election in the summer if attempts at forming a new government would fail.

The statement was seen as a last-minute effort to win over the renegades, as a snap election would threaten their seats in parliament. The next election is not due until mid-2010. (dpa)