How did Obama's endorsement of Clinton interfere with people's choices? There's nothing that says you have to listen to him. And how could he not endorse his ow

How did Obama's endorsement of Clinton interfere with people's choices? There's nothing that says you have to listen to him. And how could he not endorse his own party's candidate? And since Clinton served in his administration, anybody who had a negative opinion of Obama wouldn't have voted for her anyway.