Steering clear of the political bitterness and ideological conflict that plunged their country into bloodshed four decades ago, Spain's newly polite politicians tonight ended the first free election campaign here since the Civil War.

Although bombs in the Basque country cost one life and some street clashes in Madrid followed the end of the final rallies late tonight, the politicians maintained a tolerant attitude to the end.

Leaders of the nine main political groupings seeking seats in Parliament appeared on television to deliver 10-minute final appeals for votes. The electoral messages contained almost no direct attacks on rivals, stressing instead the virtues of moderation.

King Juan Carlos' appointed prime minister, Adolfo Suarez, appealed for new "cooperation of left and right" in building "a new horizon for Spain." He made only a glancing reference to the Communists and Socialists, portrayed as major threats to democracy and persecuted under the rule of the late Generalissimo Francisco Franco.

Communist leader Santiago Carrillo, who has sought respectability more than he sought votes in the campaign, reciprocated with a moderate promise that "We do not want any dictatorship here, not even our own."

Socialist leader Felipe Gonzalez, who has registered strong gains in public-opinion polls in recent days, also avoided attacking Suarez, whose job does not directly depend on Wednesday's election results, but who has entered the campaign to rally the Democratic Center group.

The campaign ended as it began, centering almost entirely on personalities rather than issues.

Fears of reopening old wounds and sparking new violence, and the heavy pressures the king and Suarez can bring to bear inside a system that is still only partly open, appear to have encouraged the new tolerance and inhibited ideological confrontation.

Of equal importance, however, appears to be a tacit understanding between Suarez and the Communists for an orderly campaign free of bitterness. The limited compromise, for specific electoral purposes rather than for governing, is the subject of intense interest elsewhere in Europe.

The only candidate on the 90-minute television finale to attack another group directly was conservative Manuel Fraga, whose Popular Alliance appears to have lost ground in the campaign by referring frequently to the Civil War and favorably to Franco's rule.

The tranquil pronouncements of the politicians were punctuated by bomb blasts in the country's northern Basque provinces and in Catalonia. Spanish newspaper attributed the blasts to urban terror groups intent on disrupting the elections.

A bomb planted in an empty police car exploded in the Basque town of Barracaldo and killed a passerby. Other targets hit in the Basque area were a VCivil War monument, a television relay tower and the main rail line to Madrid, which was put out of operation for several hours.

Grenades were thrown into a police parking lot in Pamplona, and law courts were damaged in Barcelona and Valencia.

Police and army units have been put on a routine alert across the country, but the government gave no indication that it expected serious efforts to disruption Wednesday's balloting for the 350 seats in the Chamber of Deputies and the 207-member Senate.

Last-minute public-opinion polls commissioned by news organizations and some parties give a wide spread of possible results. Most indicate that Suarez should gain about a third of the popular vote, with the Socialists finishing second.

The lack of issues has helped complicate the opinion polling, but it has clearly been welcomed both by Suarez, as he seeks to convince the middle and upper classes that he can keep order without the oppressiveness of the Franco system, and by Carrillo, who has had to try to overcome rightist charges of a totalitarian and violent record in the Civil War.

They deny that any bargains were struck when Suarez unexpectedly legalized the Communist Party in April. But since then there have been no political Communists; Carrillo has appeared to move to keep Dolores Ibarruri, known as La Pasionaria, in the background since her return from Moscow; and the Communists are not running any candidates for the Senate.

Garrillo has carefully studied the success of the Italian Communist Party, which has unsuccessfully proposed a "historic compromise" with the ruling Christian Democrats. While still far from a similar situation, the compromise is miniature achieved in the campaign has encouraged the Spanish Communists.

In the only section of his speech tonight that could be considered partisan, Suarez appeared to underline both the success of the campaign tolerance and the problems of trying to carry it over into the post-election period.

"To the right of us are parties promising to pursue reforms we know are insufficient," Suarez said "to the left are parties that in the short-term are moderate but that do not hide that they want to create a society dominated by Marxism."