Last week's primaries did more than just eliminate two of the four candidates vying to relieve Gov. Michael S. Dukakis at the helm of the Massachusetts ship of state. It also threw overboard a number of the signal flags that had separated one party from another in the campaign's early days.

On the subject of abortion, both Democratic nominee John R. Silber and his Republican opponent, former U.S. attorney William F. Weld '66, describe themselves as avidly prochoice. Both maintain they are fiscal conservatives who can rescue the state from its budget crisis by trimming government waste. And each says he can do this without cutting vital services to the state's most needy residents.

In the absence of any stark differences between the two candidates on these concerns, a ballot referendum proposed by Citizens for Limited Taxation (CLT) has emerged as the touchstone of the campaign.

Weld has voiced strong support for the petition, which would roll state taxes and fees back to their June 1988 levels. The Cambridge Republican says it is the only way Massachusetts can force the legislature to cut the deadwood from the state's budget and save it from fiscal ruin.

Silber counters that the CLT petition, which will appear as Question 3 on the November ballot, would be state-sponsored suicide, a move that would cut an estimated $2 billion in revenue from the Massachusetts budget. Supporters say Silber, now on leave as president of Boston University, can use his well-honed administrative skills to trim the $2 billion in a more gradual and humane way.

"I think it's going to be a cutting edge issue," said Michael Goldman, a political consultant who worked for Lt. Gov. Evelyn F. Murphy during her campaign for the corner office.

Support for the petition was high shortly after the primary last week, according to a poll by The Boston Globe which showed supporters of the CLT petition leading opponents by 16 percentage points. More recent polls, however, have shown that gap closing.

A Cry of Anger

The CLT petition was born from the same public anger that put Proposition 2 1/2 on the books almost a decade ago. Approved by almost 60 percent of voters in a 1980 referendum, Prop 2 1/2 set a limit on the amount of revenue a city or town can raise through property taxes and puts a cap on the annual property tax increase for that city or town.

But opponents of the CLT petition--among them many state legislators--say that with today's budget deficit, now estimated at anywhere from $700 million to $2 billion, the state cannot afford to lose the revenue Question 3 could take away.

"I think it would be disastrous," said State Sen. Michael LoPresti '70 (D-Boston). "Many, many people would be hurt."

"Every program you could think of, from students to the elderly, will be hurt," LoPresti said.

But LoPresti said the legislature is currently hesitant about developing an alternative to the CLT petition, saying that lawmakers are waiting to see the results of the ballot referendum.

If voters reject the petition, the legislature will have leverage to reorganize expensive state accounts and make gradual, sensible cuts in the budget, LoPresti said. If voters embrace the measure on the November ballot, LoPresti said legislators are unsure what will happen.

"If CLT passes, we're afraid of chaos," he said.