US Governement discussion question

Our two-party system tends to draw the voting population toward either the Democratic or Republican party. However, many people refer to themselves as politically Independent when polled.

Take a look at the most recent Gallup poll on Party Affiliation. What keeps Independents from saying that they align with either the Democrats or the Republicans? Or do they really align with one side? Explain your response.

Is the two-party system working? Why or why not? 

https://news.gallup.com/poll/15370/party-affiliation.aspx