The Democrats always seem to place the political role in primacy, under the theory that you have to beat your opponent or you won't have to worry about uniting a nation anyway. This is why they both concentrate on and are so good at bludgeoning and mudslinging for election purposes. They are "better" politicians than most Republicans. Some Republicans, like both Bushes, once having won an election view the national role as primary -- often this is called "staying above the fray" and seems to denote a view that the down-and-dirty of raw politics is unsavory and beneath the President.
Not all Republicans are this way: Reagan blended both roles very well, though he wasn't tremendously successful at electioneering for his party in Congress. Newt was an example of a Republican that played the game more like the Democrats do -- and was unimaginably successful, until the Rats put a bullseye on him out of their own terror.
For better or worse, W views things the way he views them. If he is successful, particularly in the economy and war, then like Reagan he will win big the second time around on his own merits. However, he may not translate that into victories for his party in Congress.
The president wants to increase the size of Government...
The GOP troops want to increase the size of Government...
What's there to disagree about???