And if so, what does this mean for the Constitution?
This is prompted by the remarks of Senator Robert Byrd. (Note that we’re not talking about a Republican looking for an opportunity to slam Obama here, this guy is a Democrat and a Constitutional scholar.)
Please correct me if I’m wrong, but this seems to be par for the course for all modern Presidents, whatever their political complexion. Is Byrd being alarmist or is this a real ongoing threat to the Constitution?
I can’t speak for America, but it seems to me that it is in the nature of politicians and political structures to try to expand their power, so at one time power will flow one way and at another time it will flow another way.
Presidential power was weakened under Nixon, Ford and Carter. Nixon damaged it through his own actions, and Ford and Carter weren’t able to rein in a Congress hell bent on restricting presidential power in the wake of Watergate. Both men were also quite different from Nixon, and while they did at times defend presidential prerogatives they did not wish to appear as overreaching as Nixon was.
So no, this isn’t a hard rule across the board, even in recent history.
Mm, this is before my time (as in, fifteen years before I was born), but it seems to me that Nixon’s presidential power expanded just fine; his expansions did not last to his successors because of his poisonous nature and Congress rediscovering its balls. This is just a quibble, mind you, but it seems like your summary was a bit inaccurate.
I think one of the big problems, probably the big problem here, is Congress. I think the problem really started back with the 17th Amendment. Presidential power went up and down (particularly up with Lincoln and particularly down with Andrew Johnson 
) but the 17th AMendment changed things, and not in a good way. The shift was not immediate.
The great advantage of the Senate was that itwas always a deliberative body. It didn’t need to consider voters’ immediate wishes, and it was a potent voice for the states in moderating and influencing the Federal government. And I think that was a very good thing. It countered or altered many of the power blocs we now see reigning over Congress. Senators were politicians, but a different kind of politician. They had to impress and deal with a different group.
Overall, I don’t think the general balance of the body changed, but the type of men and women it attracted did. Before this, they may have sold influence, but they had a couple hundred (state representatives/senators) looking at them closely, rather than thousands or millions looking shallowly. Corruption was different and probably less virulent. But mostly, the people in it were usually both cunning and very knowledgeable and diplomatic. Even Alexis de Toqueville noted this trend.
The problem, as I see it, is that today we have two bodies of Representatives and functionally no Senate. I understand, and even admire, the motives of the people who made the change. It’s their judgement I question. I like democracy, but different areas of government were made accountable to different groups: The House to the people directly, the Senate to the states, the President to the Electoral College. Frankly, I think we ought to celebrate the differences.
Please explain how this power expanded, apart from an abuse of it that was later punished.
And you don’t think that there’s a subset of a few hundred out of those millions who are looking just as deeply as the state legislatures used to? It seems bizarre to me to argue that senatorial scrutiny is now weaker by virtue of being accountable to a larger group.
To the issue which prompted the OP, I don’t see that creating White House offices on various topics necessarily represents an increase in presidential power at all. As President, Obama will have to make decisions on a wide variety of topics (including health care, urban affairs, and the environment), even if those decisions are only whether to sign or veto a bill. He is not himself an expert on most of the issues on which he will need to make decisions, so he bases his decisions at least in part on the advice of those who are experts. By establishing these offices, all he’s doing is keeping his advisors close to him, where they can more effectively advise him.
No doubt, but their power to affect anything is vastly less. Even with the internet. And being accountable to a larger group often does create a situation of “Not-my-problemism.”