Of course, as that link states, there's not much stopping me from changing party affiliation at any time and voting in whatever primary I choose. (politics.stackexchange.com)
However, there's one problem a lot of people are facing: If you're already a registered voter, you can't change parties in time for next month's primary. (spectrumlocalnews.com)
He's also pushed make it easier for a voter to change their party registration before a primary. (nydailynews.com)