By this weekend, it has become a little clearer whether the almost unprecedented response to ETA's killing of Miguel Angel Blanco has really wrought a fundamental change in attitudes in the Basque country. The huge rolling waves of furious protest at this young town councillor's abduction and murder on Saturday have subsided. During the week, the political focus began to shift to the expected counter-current from ETA's supporters.

Herri Batasuna, the political coalition accused by the other Basque parties of being ETA's accomplices, announced a rally for this afternoon in San Sebastian. On Wednesday, the Basque government banned the HB march because, given the current political temperature, it would be impossible to guarantee public order. The clear implication was that the Basque government's police force might not be able to protect HB members from the wrath of a public outraged by the coalition's refusal to condemn ETA for Blanco's murder.

The scene still seemed set for a major confrontation, however, since HB has a history of defying such prohibitions. However, on Thursday the organisers announced they would challenge the ban only in the courts. In a familiar vicious circle, they argue that they are being denied democratic rights.

Yesterday's court decision went against them, and a HB spokesman told The Irish Times last night it will respect the ban on this occasion. He added that an ongoing "March for Liberty", currently near San Sebastian, would not become an alternative demonstration. But he said that HB would go ahead with some form of public mobilisation next weekend, with or without legal permission.

Effectively, however, this means that HB has accepted a cooling off period. Perhaps its leaders were not confident they could muster sufficient numbers under the circumstances. Perhaps they really are reassessing the road which has brought it to the brink of full-scale civil conflict, not with the security forces but with its fellow Basques. If so, this is the first significant indication of how far last week's enormous outpouring of anti-ETA feeling has dented support for the radicals in their heartland.

There can be little doubt that the naked anger and scale of the anti-ETA demonstrations in the Basque country itself have caught HB off guard in the short term. HB could live with, and even capitalise on, hostile mass demonstrations in other parts of the Spanish State, which it considers an oppressive foreign power.

But to have its own offices, bars and social clubs, in many of its own strongholds, shut down for days by angry Basques, and protected from arson by a police force it reviles; to have some of its local and national leaders hiding in their homes for fear of abuse and assault - that is a breath-taking reversal.

For Herri Batasuna, which translates as People United, believes the streets belong to it. In the mid-90s it has adapted a new strategy, which explicitly calls for "socialisation of the conflict between Euskadi [the Basque country] and Spain". In plain language, this has meant the launching of a youth Intifada, spearheaded by Jarrai, a kind of junior ETA. The resultant kalea borroka (street struggle) is a widespread campaign of sabotage and violence. It involves arson attacks on banks, buses, or simply cars with French number plates (because France now regularly extradites ETA suspects).

Meanwhile, any individual wearing a blue lapel ribbon, the symbol of support for the release of ETA's kidnap victims, risks getting a beating from gangs of teenagers in the old quarters of Bilbao or San Sebastian. The most disturbing aspect of this strategy, however, has been the calling of aggressive counter-demonstrations against any public display of rejection of ETA.

A remarkable quasi-pacifist organisation has emerged in recent years, which holds silent vigils for all victims of the conflict, whether policemen, members of ETA, or civilians caught in crossfire. These vigils have frequently been the targets of ferocious verbal and even physical intimidation from HB supporters, and have had to be abandoned in some cases.

Since last week, however, HB has found that the socialisation of the conflict can cut both ways. There have been very big anti-ETA demonstrations in the Basque country in the past, but there has never been such a sustained and evidently spontaneous ostracisation of the organisation's supporters.

A key question, however, is whether this dramatic shift in street politics is actually causing HB supporters to rethink their positions, or whether it will simply push them deeper into their bunkers.

So far, the signs are unclear. Only a handful of HB members, and of already disaffected ETA prisoners, have publicly condemned Miguel Angel Blanco's murder, well short of an obvious sea-change. HB's decision not to go on the streets illegally today is a more reliable indicator.

So is an editorial in a newspaper close to HB, which appears to acknowledge the democratic validity of the anti-ETA demonstrations. But HB leaders continued to portray the demonstrators as the dupes of Hitlerian mass manipulation; whether its supporters swallow this line remains to be seen.

In any case, the habit of conflict politics will not be easily broken. ETA still adheres to the crude dialectic of a spiral of action-repression-action, whereby its violent operations bring down repression on its followers, leading to more support and a greater capacity for future action.

So far, most leaders of the anti-ETA demonstrations have been acutely conscious of the danger of feeding into this spiral, and have explicitly called for restraint.

"We mustn't allow ourselves to fall into the same behaviour as those who destroy cars, and political offices, and beat up defenceless people, because then they [ETA] will have won," a pacifist representative said on Tuesday.

The conservative Popular Party, which governs in Madrid and has often used robust public order rhetoric in the past, has repeatedly asked its supporters to act strictly within the law.

Not everyone has been so sensitive. The former Socialist prime minister, Felipe Gonzalez, chose last Tuesday to reassert publicly his support for his former ministers, civil servants, and generals charged in court with organising GAL, the death squads which murdered ETA members and ordinary citizens alike in the 1980s.

It would probably only take the lynching of a single HB member by an angry mob to turn the radicals from villains to victims again in the eyes of any wavering supporters. The prospect of continuing civil conflict between the large minority (probably more than 12 per cent) of Basques who support HB, and their fellow citizens, is fraught with danger. Nor can it be assumed that moderate nationalists might not wobble back towards ETA if such a conflict were prolonged and violent.

Basque society may be polarised today, but it is also powerfully homogenous. Many families who back the moderates will have at least one close relative involved to some degree in armed struggle, and still regard ETA as prodigal sons rather than real enemies. Ambiguity towards the political use of murder melted away last week, but any return to illegal attacks on ETA and HB could bring it down again like a lethal mist.

The historian Gabriel Jackson, writing last January, put it this way: "Between ETA and the legacy of GAL, Spanish democracy is in serious danger for the first time since the end of Franco's dictatorship."

Last week's extraordinarily moving demonstrations made it a little safer, but there is still a minefield between the Basque country and peace.