A national strike called by Chilean unions was stalled here today while political and labor leaders worked to form a united front of business and labor organizations to confront the government of Gen. Augusto Pinochet.

In the second day of a work stoppage designed to force economic and labor reforms and a move toward democracy, strike organizers conceded that they had failed to shut down economic activities or win widespread support from Chilean unions and political parties.

But while one major sector--commercial trucking--continued to be affected by the strike, union, business and professional leaders negotiated the formation of a multisector front that would present a list of demands to the military government.

"This is our first victory," said Rodolfo Quinteros, the president of the truckers' union and the principal figure in this week's strike movement. "We are approaching a historic agreement among sectors that will transform the political situation."

Quinteros said that his union expected to receive tonight a draft document representing Chile's professional associations, small businessmen, farmers and other groups and that the country's transportation union would consider merging with the new organization this weekend.

At the same time, Quinteros said the transportation union was continuing negotiations with the government on an end to the current work stoppage. The strike has paralyzed most of Chile's vital trucking network and caused partial stoppages in other sectors.

The labor leaders said in an interview that the government had indicated it would accept union demands, which include the release of jailed union leaders and an end to newly tightened censorship.

The talks on forming the multisector front reflected the influence of Chile's proscribed but still active opposition political parties and many union organizations that so far have opposed the strike on tactical grounds. These groups have been working to consolidate an opposition movement against Pinochet and prepare a major antigovernment protest next month.

If successful, the talks on the front formation would unite major Chilean economic sectors against the government in a movement mirroring an alliance whose opposition to the socialist government of Salvador Allende helped bring Pinochet to power 10 years ago.

Political analysts emphasized today that 10 days of turbulent protest and confrontation between the government and its opposition have left both sides damaged and disoriented.

The Pinochet government effectively halted this week's attempt at a national strike by banning its coverage in the news media and bringing court charges against labor leaders.

The government also succeeded in demobilizing Chile's powerful 23,000-member copper workers' union, whose leadership was at the center of massive antigovernment demonstrations last month and last week.

The copper workers managed only a temporary and partial shutdown of Chile's economically crucial mining center after calling a strike last week, and its leadership now stands dismantled by firings and jailings.

However, the protests and strike have been successful in producing government movement toward political liberalization rejected by Pinochet only months ago.

The 67-year-old leader's once unquestioned power as president of the military government now appears to have been checked. Well-informed sources say the Chilean Navy, backed by the Air Force and acting through the government's long-subordinated military junta, appeared to have blocked a Pinochet initiative to declare a state of siege and initiate a full crackdown on the opposition.

Among civilian leaders a consensus is growing that Pinochet's official mandate to rule until 1989 will have to be shortened and the military will have to compromise with its opposition, perhaps by appointing a civilian prime minister who would replace Pinochet in the day-to-day operation of the government.

Opposition leaders, in contrast, believe that if their attempt to organize a continuing series of national protests against the government is successful, the armed forces could be provoked to remove Pinochet and move the country toward democracy in the relatively near future.

Chilean political party leaders ranging from the right to the socialist left are already organized in a multiparty coalition, and they have begun work on an alternative program of government they hope to announce next month along with a call for Pinochet's resignation.

"The government and the opposition have both taken losses," a leader of the Christian Democratic Party said. "But we aren't satisfied with what has happened--in spite of our victims."