This post describes calling a few minutes before the line opens, then navigating the phone tree, then asking for it to repeat options repeatedly until the exact moment the phone lines open, so as to be one of the first handful in line. Could try this tomorrow morning if you can't get through today:

https://www.flyertalk.com/forum/33599906-post1632.html

ETA:

If your travel is for a "life or death emergency" as defined by the State Dept, there is another number you can call: https://travel.state.gov/content/travel/en/passports/get-fast/emergencies.html