Spanish Prime Minister-designate Leopoldo Calvo-Sotelo today told a tense session of the Congress of Deputies that a "new epoch" was starting in the delicate transition from dictatorship to democracy.

Calvo-Sotelo appealed for support from the lower house of the Cortes (parliament) which is scheduled to vote Friday on his nomination by King Juan Carlos as successor to outgoing Prime Minister Adolfo Suarez who resigned last month after nearly five years in office.

The crucial debate marks a point at which Spain's changeover to a parliamentary system begins to tread new ground with the departure of Suarez who was the main architect of the electroral system that replaced the government of Generalissimo Francisco Franco.

Calvo-Sotelo, who was Suarez's deputy premier and chief minister responsible for the economy, faces the uphill task of gaining the confidence of the 350-member Congress where the Union of the Democratic Center party to which both he and Suarez belong, lacks an overall majority. In the political vacuum created by Suarez' sudden resignation and atmosphere of questions about government credibility, which touches on the volatile issue of terrorism and the police, minor parties in Congress have already signaled that they will withhold support for Calvo-Sotelo and deny him the majority he has requested.

Calvo-Sotelo, a dour engineer and well-connected businessman who has had several Cabinet posts under Suarez, lacks the populist charisma that enabled his predecessor to charm opponents and doubters alike through the post-Franco transition. His 90-minute speech to the Congress emphasized a tight monetarist economic policy and a determined pro-Western foreign policy that included the decision, should he form a government, to enter NATO. Suarez, in his bid to maintain consensus politics in the transition period, had consistently ducked such difficult decisions.

The apparent bid to pursue conservative policies comes at a time of intense political squabbling and concern over the destabilizing effects of terrorism coupled to what has amounted to a revolt among senior policemen charged with curbing the gunmen. Recent disturbing events have included the death of a Basque terrorist suspect while in police custody, a mass protest movement -- including a 24-hour general strike in the Basque region -- the arrest of the police officiers responsible for interrogating the suspect and the protest resignation of at least seven senior police officials.

The palpable evidence that torture is still practiced in Spain by the police has created a political storm of unprecedented proportions. The suspect, Jose Arregui, died from bronchial pneumonia and an autopsy report said he had undergone physical violence which included burns on the soles of his feet.

The leftist opposition has begun to call for a purge of the police force, which remains Francoist trained, thereby breaking a tacit understanding among political parties that such sensitive issues should be left untouched in the interests of consolidating democracy.

The outcry has served to restore the tarnished reputation of the Basque separatist movement ETA, to which Arregui belonged, and has impeded the creation of agreements in Congress between the governing party and regional groupings that are vital for the majority backing that Calvo-Sotelo requires. The resignation of the senior police officers was termed "blackmail" by Socialist and Communist leaders yesterday, while it received the enthusiastic backing of ultra-rightists who are intensely critical of Spain's democratic experiment.

Facing such an unpropitious moment, Calvo-Sotelo, 54, said it was his intention to form a government drawn solely from his own party and that he intended to govern through to 1983 when new elections are constitutionally due.

The consensus view among Spanish political commentators is, however, that Calvo-Sotelo, governing alone with his party, will be unable to provide a stable government.