Other than driving or Amtrak the two options as I see it are:

1) Call CO and ask about moving to an earlier flight to avoid a possible misconnect. They might say no, they might ask for $$, they might tell you to call DL or NW, but hey, they might say yes.

2) Assuming flights iad-ewr aren't full, show up early and stand by at the gate for an earlier flight. I believe you can confirm that same-day for $25, but I've always just gone to the gate. If there are seats, you're on. Just make really, really sure that they update your PNR correctly so that you're not still on the orignal flight after getting on the earlier flight. If so they *might* cancel the remaining segments. It's usually done correctly, but there is the occasional thread posted here where something went wrong.