Look at the red-versus-blue maps that every television network has been displaying since last night. The blue (voted Kerry) states are basically those that have viable intercity regional rail service -- the Northeast, the upper Midwest, California, and the Pacific Northwest. The red states (voted Bush) as a general rule have only minimal service, a long distance train or two here or there. We know who's running the show for the next four years.
I don't want to swap cause and effect here -- urban areas tend to vote Democratic and urban areas tend to have viable rail corridors. But the fact is, for most of America, Amtrak is probably about number fifty on their list of political concerns, and the areas where it *is* a significant concern don't represent a majority of the electorate.
Regional corridors in the Northeast, Chicago area, California, and Northwest are probably safe, in my opinion, because their high ridership constitutes a political support base. But as for a national system still existing four years from now, I wouldn't bet on it unless something big changes. If nothing else, the accelerating equipment shortage and the passive hostility of the freight mega-railroads will kill most long distance service in the absence of aggressive support from Congress.