For almost a century, from 1870 to 1950, most Massachusetts governors used the lieutenant governorship as a stepping stone to the state's top executive post. The pattern has waned in recent years, but Thomas P. O'Neill III, the current number-two-man in the Commonwealth and part of a well-known political clan in these parts, would like to revive the tradition.

Like most lieutenant governors, O'Neill's effectiveness has depended heavily on his relationship with his boss. Elected with Michael S. Dukakis in 1974, he strengthened the Commonwealth's Washington ties and received rave reviews from conservatives and liberals for increasing the flow of federal dollars into the Massachusetts treasury.

But after winning re-election on a ticket with Edward King, an ideological opponent, O'Neill has lost most of the power he once enjoyed.

Moreover, O'Neill has clearly shown that his ambitions go beyond charring occasional Governor's Council meetings. The son of the Speaker of the House seriously considered running for the Senate seat now occupied by Paul Tsongas. After he gave up on that idea, most observers expected O'Neill to shoot for the governorship, and he officially confirmed his intentions last October.

The road O'Neill has taken since then has surprised few people, but his career has undergone heavily critical reappraisal. The son of one of the nation's most successful old-style liberal politicians, he has been saddled with the image of a lightweight riding on a powerful family name. His greatest task, some have said, is to provide voters with a concrete reason for supporting him, besides the fact that he wants to win.

In the past few months, O'Neill has finally provided the platform potential supporters have been looking for: a tax reform plan which would generate increased revenues by raising sales levies on luxury goods. Under his scheme, the state would use the luxury tax to provide income tax relief to private citizens.

The plan received a warm reception from the left, but O'Neill failed to overcome his image problem in the recent ward caucuses Dukakis, though he rarely addressed issues at all, left no more than 10 per cent of the delegates for O'Neill.

Failing to demonstrate a significant base of support, most of O'Neill's financial sources have dried up, making his campaign even more dubious.

The next test of O'Neill's viability will come tonight, when his father returns from Washington to help raise funds. Even if the bash succeeds in drawing big money, it probably won't be sufficient to put the campaign in the black.

The candidate insists he is in the race to stay, but his is a quest fast becoming futile.