They have been called many things: amoebas, spineless cowards, weaklings, and other names not suitable for print in a family newspaper.
The modern characterization for many politicians who refuse to take a stand, especially in the midst of the growing and rapid threat of American socialism, is the word “weenie.”
People fear being called names for expressing personal convictions (assuming they have any) and so they either say nothing or they go along to get along.