Elections watched for signal on Brazil reforms. Mayoral voting will gauge support for Sarney's plans

The outcome of Brazil's mayoral elections tomorrow is expected to indicate whether voters want the government to press ahead with reforms or maintain the status quo. The election results will offer a glimpse of how Brazilians feel President Jos'e Sarney's new administration is doing. (President Sarney, the first civilian ruler in 21 years, has been in office for eight months.)

If his hand is strengthened by the election, Mr. Sarney may be able to move faster and farther along the road to political and social reform. So far, his efforts have been hampered.

His attempts to implement land reform proposals have been undercut by conservative opposition. His efforts to cut away the prerogatives enjoyed by elected and appointed officials has been undermined. And his efforts to draft a new constitution have been delayed.

The land question is the most critical. Recent weeks have been marked by clashes between peasant squatters and the hired gunmen of landowners. Under the new reform scheme, only idle farm land is subject to expropriation (with compensation) and distribution.

Some 18 million Brazilians are registered to vote in the first mayoral elections in 21 years. (Voting is obligatory.) It is generally speculated that the winners for the top political jobs in 201 cities, including the 25 state capitals, are:

The Brazilian Democratic Movement Party, the government's center-left party that has the largest contingent in the National Congress. Together with the Liberal Front Party, it forms the ruling coalition called the Democratic Alliance.

The Liberal Front Party, a breakaway segment of the now-defunct, conservative Democratic Social Party, which was an arm of the ruling military.

The Democratic Labor Party led by socialist Leonel Brizola, governor of Rio de Janeiro State.

The Brazilian Labor Party, right-leaning, labor-oriented.

There are 25 other local parties that were pieced together for the elections. They are unlikely to win a single victory.

It is generally thought that the Brazilian Democratic Movement will sweep the northeast and center-west regions. Its coalition ally, the Liberal Front Party, is not expected to do nearly as well.

Sarney is more closely linked with the Liberal Front Party than with the Brazilian Democratic Movement. He was once the head of the pro-military Democratic Social Party before becoming President last March.

It is speculated that the Democratic Labor Party candidates will win the mayorships of Rio de Janeiro City and Porto Alegre, capital of the southernmost state of Rio Grande do Sul.

But attention is riveted on Sao Paulo, where the election race is very close between the government and opposition candidates.

If the opposition candidate wins, he could weaken and perhaps wreck the already-shaky government alliance.