amandas262, actually you aren't in this perspective.
The department of homeland security requires a letter from the absent parent authorizing you to get a passport for your child.
Just pray you don't need a passport yet and that the law isn't passed by the time you leave.
If they do pass the law you will require a passport for your child and you will need form 8653 I believe signed by your x.
If you don't have that stuff you wont be able to get a passport for your child.
And I am afraid to tell you no court will force your x to consent to a passport because that makes you a flight risk with the child and no court will be held liable for that.
Also if you decide to go without a passport and a emergency happens you will not be able to fly back into the United States a passport card will not even allow that.
I only state this stuff because I was in a similiar situation that you are in.