Two-thirds of the announced lineup for the Freedom 250 concert series have dropped out, with most artists citing concerns about being tied to an event billed as nonpartisan but described by critics as a MAGA celebration. Why it matters: President Trump has promoted the nation's 250th birthday events as a grand patriotic affair, but the withdrawals underscore artists' fears of alienating fans amid partisan divides . Six scheduled performers — Morris Day, Young MC, Martina McBride, Bret Michaels, Milli Vanilli and The Commodores — have withdrawn since the concert lineup was announced Wednesday. C+C Music Factory, Vanilla Ice and Flo Rida remain scheduled to perform.…