Is there a way to place the value of a variable as a criterion in the Query Design Window

I am trying to use the value of a variable as a criterion in the Query Design Window.

For example, I have the variable, ID_Flag, and I would like the ID column in the query to be equal to the value of ID_Flag as the critieria. However, Access won't allow me to do that. It keeps putting quotes around the variable name so it looks like this "ID_Flag". How do I get around this?

Thanks.