NEW YORK--Arkansas Gov. Bill Clinton cleared a crucial hurdle on his path to the Democratic presidential nomination yesterday, sweeping four primaries, including an important contest in New York.

Insurgent candidate Edmund G. Brown Jr., who gained momentum and respectability with recent victories in Connecticut and Vermont, suffered a serious--if not campaign-ending--blow. The former California governor dropped to third place in New York, finishing behind a candidate who suspended his campaign last month.

Former Massachusetts Sen. Paul E.

Tsongas edged out Brown by three percentagepoints, apparently winning the none-of-the-aboveprotest vote that Brown rode to victory inConnecticut. Tsongas said he would decide by theend of the week whether to re-enter the race.

Whatever he decides, it is unlikely to hurtClinton's chances of winning the nomination. Thefrontrunner now has 1264 of the 2145 delegatesneeded to win a first ballot nomination at thenational convention in July.

Only a major scandal could knock the Arkansasgovernor off track.

Clinton's evasive answers about marijuana useand a 1969 draft notice--issues exploited by theNew York press last week--only contributed tovoter unease about what pundits call "thecharacter question."

Only about 50 percent of Democratic voters inNew York, Wisconsin and Kansas think Clinton hasthe integrity and honesty to serve effectively aspresident, exit polls indicated.

Clinton survived the rough-and-tumble world ofNew York politics, partly by challenging the fieryBrown to a series of seven debates in the finalweek.

He took a beating in the notorious New Yorktabloids, but the same newspapers--saveone--endorsed his candidacy.

Tsongas called his second place showing hereextraordinary, but it came only after he stayedout of a brawling two weeks of "sleaze"campaigning that left both Clinton and Brownbruised.

According to exit polls, 48 percent of voterswho supported Tsongas said they were voting forhim because they disliked the other two choices.

And 66 percent of all Democrats voting in NewYork said they wanted to see another candidateenter the race. In Wisconsin and Kansas, 58 and 60percent said the same.

The only chance left for Brown--and Tsongas ifhe throws his hat back in the ring--to win thenomination would be a major tactical error orpersonal scandal in the Clinton campaign.

`Robo-Candidate'?

Clinton has established a reputation as a"robo-candidate," weathering scrutiny of hismarital fidelity, draft record and financialethics--not to mention the marijuana he "didn'tinhale" while a student at Oxford.

Pundits across the country may already bewriting the political obituary of Jerry Brown.While Brown has been criticized for changing hisposition on several key issues, two stands takenearly in the campaign which he refused to modifyled to his defeat yesterday.

His willingness to have 1988 presidentialcandidate Jesse Jackson as a running mate angeredand alienated the substantial Jewish population inNew York. Only 9 percent of the Jewish vote wentto Brown, while 55 percent supported Clinton.

Brown's unorthodox flat tax proposal also fellflat in New York, with only 20 percent of New YorkDemocrats finding it more fair than the currenttax structure.

Still, more than two-thirds of New York andWisconsin Democrats said they agreed with Brown'scentral theme--that money has corrupted thepolitical system.

It's a message that Clinton seemed ready toadopt as his own. He called every vote for Brownor Tsongas "a vote for change" and a vote he wouldrepresent in Washington