Brazilians samba to first national election in 20 years

''It's a bit like Carnival.''

So says Sandra Cavalcanti, who is campaigning to be governor of the state of Rio de Janeiro and is easily Brazil's best-known woman.

''Isn't this fun?'' she shouts as she is showered with blankets of confetti, cheers of supporters, and the flash of press cameras.

For many Brazilians, the current electoral campaign - the first nationwide election in Brazil in 20 years - is indeed proving to be a heady experience.

Their exuberance and campaign hoopla, however, does not exceed the seriousness with which they view the election. Most Brazilians seem fervently to hope that this election for many federal and state posts is the forerunner of their country's return to civilian constitutional leadership after two decades of military rule. Presidential elections are scheduled for 1984.

For Brazilians under age 40, the Nov. 15 vote will be first in which they can participate. There were some regional elections in the mid 1970s, but participation was low and other restraints made the election less than a valid test of public will.

This election is different. The turnout is expected to be high - about 70 percent of eligible voters. And restraints by Brazil's military leadership have been lifted.

Although some military men look askance at the polling, the majority, led by President Joao Baptista de Oliveira Figueiredo, are determined to nudge Brazil along the democratic path.

Just this week, General Figueiredo promised not to limit any freedom of expression. This is important in a nation that has become an economic and political force of consequence not only in Latin America but throughout the world.

As it moves toward civilian rule, albeit along a bumpy road, the impact of a return to democracy here is bound to be felt elsewhere.

Voters next week will choose governors for all but one of Brazil's 23 states, 25 senators, 479 federal deputies, 974 state deputies, and more than 40,000 local officials.

This maze of candidates ''is bewildering,'' says Maria do Carmen Souza da Melo, a housewife, as she holds some 15 campaign flyers she picked up in a two-block walk along one of the main streets of the Copacabana section of Rio. ''There are so many parties, so many candidates, I am wondering how to choose.''

Then she pauses: ''But I guess I will vote for Sandra.''

So are a lot of voters going to the polls. But Sandra Cavalcanti is no longer the favorite. She recognizes that she faces an uphill battle for the governorship against four other candidates, including Leonel Brizola, a controversial leftist who at the time of the military takeover in 1964 was governor of another state, Rio Grande do Sul.

Conventional wisdom here puts Mr. Brizola in the lead, but his momentum may be fading and the race is still regarded as undecided a week before the ballot boxes are yanked out of retirement. Opinion polls show at least 10 percent of the electorate in Rio as uncertain which way to vote.

In addition to Sandra Cavalcanti and Leonel Brizola, there are many other well-known Brazilians running for office:

Janio Quadros - a former president who some Brazilians blame for opening the door to military rule by resigning shortly after taking office - is running for governor of the state of Sao Paulo, where half of the country's industry is concentrated.

Roberto de Oliveira Campos, planning minister under the military in the late 1960s who helped launch the 1970s' economic boom, is running for the Senate from the frontier state of Mato Grosso, arguing that anyone ''wanting to be in government has to test the electoral waters.''

Former Cabinet members like Jarbas Passarinho and Ney Braga are in uphill senatorial races in Bahia and Paran.

But there are also a lot of new faces. More than half the candidates are new to politics - many were not of voting age when the military seized power. Fewer than 5 percent of the candidates are women, but even ''this (number) can be regarded as amazing given the traditional male preference in Brazil,'' notes the newspaper El Pernanbucano.