You can call him a tyrannical extremist, or you can call him a brilliant visionary.

But after this week's poll ranking him above Lt. Gov. Evelyn Murphy in the Democratic gubernatorial contest, one thing you can no longer call Boston University President John R. Silber is a fringe candidate.

According to the poll, which appeared in Monday's Boston Herald, Silber can expect support from 24 percent of the voters--above Murphy's 19 percent, but well behind the 36 percent of frontrunner and former Attorney General Francis X. Bellotti.

"You can see the momentum picking up--the hard work has paid off," said Colin B. Reilly, a spokesperson for Silber. "When Frank Bellotti looks over his shoulder, the face he sees is John Silber."

But before Silber can disregard Murphy's candidacy--let alone gain a place on the ballot for September's primary--he must obtain support from 15 percent of the delegates at next month's state Democratic convention.

The convention is expected to stress the viewpoints of the state's more liberal Democrats, and analysts say Murphy will get strong support from her extensive grass-roots network among party activists.

Though official delegate counts are unavailable, many estimates indicate that Murphy and Bellotti have comparable support. But the B.U. president will have to fight just to get 15 percent, although officials for both Silber and Murphy have said he has a good chance of making the cut.

Campaign observers acknowledged that the survey's results represent a boost to his campaign. However, they said that polls alone do not make Silber a serious contender.

"I think the notion that [the poll] justifies putting Silber on the ballot is a bit inflated," said Daniel B. Payne, an independent Democratic consultant. "Silber still has to prove to a sizeable portion of the delegates that he has the values and ideals of the Democratic party," he added.

And Murphy consultant Michael Goldman said, "There is no question that this particular survey was intended to pressure the convention to give him 15 percent he hasn't earned."

Silber and supporters such as State Senate President William M. Bulger (D-Boston) have voiced their opposition to the "15 percent rule" from the campaign's start, claiming it is an "exclusionary" measure that limits voter choice.

The poll's most important finding, most observers agreed, is that it highlights the problems the Murphy campaign is currently facing. Observers have said that her campaign has "stalled" in recent weeks.

But Murphy supporters downplayed the poll's results, attributing Silber's rise to a "media bump" from the two-week, $200,000 television advertising campaign he began in early April.

The supporters said that the lieutenant governor--who began her own television blitz last week--will get a similar boost. They also protested the timing of the poll as unfair.

But others predicted that Silber's success in the Herald poll would negatively influence perceptions about Murphy, making it difficult for her to regain ground on television.

"The poll is, no doubt, going to affect whether or not Murphy can get a positive reaction," said Payne. "This news is going to interdict and water down the effect of her TV buy."

Payne added that Bellotti has maintained a strong lead, a lead that Bellotti supporters said was not likely to be effaced by Murphy or Silber, whatever their media efforts.