They are more afraid of Republicans calling Dems socialist (They already do), rather than seeing the opinion of the people. They need to stop playing by the GOP's rulebook.
The BulwarkThe vibes may be exciting, but if Democrats are going to win this year and in 2028, they must reject the DSA. If you’re tempted by a democratic socialist this year, think of what use Republicans will make of these victories, and ask whether you want to do favors for fascists.