Two Massachusetts political figures went on trial here today for extortion in connection with an alleged plot to buy the 1972 Republican vice presidential nomination for then Transportation Secretary John A. Volpe.

Albert P. (Toots) Manzi, 68, and William V. Masiello, 48, were indicted by a state grand jury last April on charges of extorting $10,000 from Makee, Berger and Mansueto, a New York consulting firm by threatening to use their political muscle to financially destroy the company in Massachusetts if it did not comply.

Manzi was a prolific fund-raiser for Volpe's campaign for governor of Massachusetts and for other Republican candidates. Masiello owns a Worcester, Mass. architectural firm which has designed many state buildings over the past two decades. The two have been close to state political leaders in both parties.

The plan was to raise $500,000 in cash to pay off officials of then-President Nixon's reelection campaign as an inducement to replace then-Vice President Spiro T. Agnew with Volpe, contends Massachusetts Assistant Attorney General Stephen Delinsky.

Volpe and a spokesman for Nixon said they never heard of the alleged scheme. Nixon was said to be "shocked, surprised and apparently angry" when told of the allegations. Manzi and Masiello have denied the charges and pleaded innocent.

However, Massachusetts Attorney General Francis X. Bellotti, said that the charges by his office represented only "a brief synopsis of the evidence we will present at the trial."

Delinsky told Suffolk County Superior court at an arraignment last May:

"The commonwealth will prove that Masiello and Manzi conspired together to raise $500,000 in cash for the purpose of delivering the money to former President Richard M. Nixon before the Republican National Convention in 1972 to influence Nixon's decision to promote then Transportation Secretary John Volpe to vice president."

The charges rocked the political power centers here, which were still reeling from an earlier trial involving the consulting firm.

In that trial, then state Sens. Joseph J. C. DiCarlo and Ronald C. Mackenzie were convicted in federal court in 1972 of extorting $40,000 from the firm in 1971.

The payoff was designed to ensure a favorable legislative report from the two senators on the company's state contract to oversee construction of the $130 million Boston campus of the University of Massachusetts. The consulting firm received $6 million from the controversial contract.

According to charges Masiello and Manzi later stepped in and demanded the consulting firm contribute the $10,000 in political payoffs as the price of continuing to do business in Massachusetts.