Despite the efforts of candidates and volunteers doing last minute, sidewalk campaigning yesterday, only 21, 261 of Cambridge's 40,000 registered voters showed up at the polls yesterday.

Turnouts for primary races usually fall short of voter participation in general elections, but yesterday's showing surprised even seasoned pollsters like Bill Willard.

Willard, the warden of the Gund polling station on the corner of Quincy and Cambridge Streets, has been affiliated with the Cambridge Election Committee since 1981.

By 1 pm, after witnessing only 18 voters cast ballots-an average of three voters per hour since the station's 7 am opening-Willard was expressing dismay.

He chastised Cantabrigians for neglecting their voting privileges.

"Apathy seems to rule," Willard said. "It's like you have to beat the bushes to get people to come out [to the polls]."

While some registered voters attributed their abstention to a dearth of compelling issues in the 1998 campaigns, others cited discontent with politics in general.

One Cambridge resident blamed the sex scandal surrounding President Clinton for his disaffection.

"Politics...I don't know...so much in the news lately has just made me tired of it," said the man.

Whether the President's troubles affected the fortunes of yesterday's Democratic candidates was a matter of debate among local pundits.

Some suggested that low voter turnout as a result of the White House controversy would do more electoral harm to local Democrats than to Republicans.

Others insisted that Massachusetts, and especially Cambridge, remains so liberal that the crisis in Washington would not resonate here.

One polling station official scoffed at the idea of a fall-out effect.

"Nope, no way," he said. "There won't even be a ripple."

Among those Cantabrigians who were not dissuaded from voting by the turmoil in the nation's capital, many expressed disappointment with an uninspiring field of candidates.