The Communist Party leadership Tuesday short-circuited the balloting process in intra-party elections for the country's new Parliament by choosing all 100 candidates for the party's 100 legislative seats.

The official news agency Tass reported that the party rank and file had suggested 31,500 nominees. But these were winnowed down and finally just 100 were chosen by the 12-member ruling Politburo.Those 100 candidates were nominated by the party's 300-member Central Committee at its plenary session Tuesday, Tass said.

The general public will elect only two-thirds of the 2,250 members in the new Congress of People's Deputies, in what has been billed as the Soviet Union's first national, multiple-candidate election on March 26.

The other third will be elected by certain organizations, including the Communist Party, which has the right to choose 100 deputies.

But rank-and-file party members won't have the chance to vote on the party's candidates, Tass said. Only party leaders will cast ballots in a special meeting March 15 and 16, and they will not have a choice of candidates.

Still, President Mikhail S. Gorbachev told the Central Committee he expects a variety of political platforms to emerge in the public campaign. Tass said Gorbachev offered a draft platform to the plenum Tuesday, but details were not released.

"The Soviet people are entitled to know the objectives and tasks formulated by the party for the immediate future, and the platform it takes to elections," Gorbachev said.

"We should proceed from the prem-ise that the other social organizations will come to the elections with their own campaign documents," and individual candidates can also offer their views, Gorbachev said.

Gorbachev was referring to other national organizations, including trade unions and scientific groups, which have been empowered to directly elect deputies to the congress. The Communist Party is the only legal political party in the Soviet Union.

Gorbachev also expressed satisfaction that most candidates nominated so far in the three-month election campaign are supporters of his restructuring policy, called peres-troika.

Under the political reform he championed, the new congress will meet once a year to elect a working parliament of 424 members and retaining the name of the old rubber-stamp parliament, the Supreme Soviet.