The term for the person/group a political party aligns themselves with to appear concerned about the general public
Solution 1:
A shill is probably the nearest word, although like with Uncle Tom, it is difficult to avoid the connotation that the shills are knowing participants, or at least that in all the circumstances they ought to know.
You can also describe the role of the people involved. You could say they act as window dressing.
"The president used the workers as window dressing to win over public support."
Using this latter device tends to avoid the connotation that the people involved (the window dressing) are at fault.
Solution 2:
I like the word prop.
Prop: something used in creating or enhancing a desired effect
Often it has a negative association because it is generally used like "The President used the iron workers as props"; using frequently means to take advantage of.
Solution 3:
Sentence: the workers were the president's token in attempt to win over public support.
Sentence: the president used the workers as a token to win over public support
token English Oxford Living Dictionaries
- a thing serving as a visible or tangible representation of a fact, quality, feeling, etc..
This term contains the inference of appearing to align per the given context without implying fault on the group being used.
Solution 4:
I've usually heard them referred to as a "Poster Child," a reference to a proverbial propaganda poster.
someone or something that is used to represent a particular quality:
-Cambridge Dictionary online
Solution 5:
The people appearing on stage are the speaker's pawns. Consider the definitions from Merriam-Webster:
1 : one of the chessmen of least value having the power to move only forward ordinarily one square at a time, to capture only diagonally forward, and to be promoted to any piece except a king upon reaching the eighth rank
2 : one that can be used to further the purposes of another
Literally, as in definition one, a pawn is a playing piece from the game of chess, often regarded as having little value but still able to be used strategically by a skilled player. Figuratively, as in definition two, a pawn is not unlike the chess piece, not really important, but able to be used by a shrewd and cunning political player to advance his or her agenda.