The identity of the President, or even the party of the President, is not as important (or at least critical) as some people think. Look at the Previous Guy, he sucked up to the ideas of the Heritage Foundation/Cato Institute types and proposed zeroing out Amtrak. That didn't happen, even when Congress was controlled by his own party.
There will, of course, be some difference between parties, as one of them seems to think that spending on passenger rail is a lower national priority, but even that party is not totally opposed to spending money on passenger rail. In many ways, it's more important who controls Congress. The President's main power is that he or she can start expensive, unwinnable wars that go on forever, and suck up so much money that it's harder to spend it on stuff like passenger rail.