Nixon, who has two children being raised in the Jewish faith, called the mailer "dirty, sleazy politics" and said Cuomo's explanation that he didn't know about the mailer isn't believable.
He also won a last-minute endorsement from rap star Nicki Minaj, who told her 20 million Twitter followers that the governor was her man.
Nixon also seemed to be gaining support for her stance on fixing the subways.
Likely to work in Cuomo's favor is that NY allows only registered Democrats to vote in the primary.
Cuomo and activist Nixon made their final pitches earlier this afternoon as their closely watched and sometimes nasty Democratic primary contest came to a close.
President Donald Trump might want to keep an eye on the attorney general primary.
Nixon's alleged support of the BDS movement was one of three bullet points used in a pro-Cuomo mailer that was sent out less than a week before Thursday's Democratic primary.
Making a pit stop at the Upper West Side eatery on Sunday while on the campaign trail, Cynthia Nixon ordered a cinnamon raisin bagel with lox and capers.
Cuomo appeared at a polling station in suburban Mount Kisco with his girlfriend, Sandra Lee.
Nixon has hammered Cuomo for failing to address New York City's beleaguered subways and for not following through on pledges to address corruption.
New York City Mayor Bill de Blasio (dih BLAH'-zee-oh) says his son ran into bureaucratic trouble at a polling site and wasn't able to cast his ballot by machine in the state's primary. The New York Times reported that the Cuomo administration offered incentives for the contractor to finish the job before the primary, and Cuomo's insistence that the state does not control the Tappan Zee contrasts with his self-presentation as an effective and engaged manager.
Best known for her stint as Miranda on HBO's "Sex and the City", the Emmy-winning Nixon has always been politically active, particularly in matters of LGBTQ rights; Nixon identifies as bisexual and is married to a woman.