I don't know this area at all, but apparently there is a commuter rail service (as mentioned) from Camden Yards, which still has a station, to Washington. But it takes an hour and a quarter, where the Amtrak train takes 45 minutes.

This is depressingly familiar situation in the UK too (not sure about the rest of Europe). Usually, it's not politics that prevent more useful connections being made, but a lack of investment to do the necessary small bits of engineering.