Joseph, Deutsch has a good chance because the leftist vote will be split between Clarke and her challengers from the left, who think she’s not leftist enough.
bsharg2, if you are not registered as a Democrat you CAN NOT vote in the Democrat primary. And it’s too late to change your registration. The deadline for that was Feb 14. (It used to be in the previous October, but they recently changed the law to move it to February.)