Is Obama acting within the constitution?

It all comes down to this one issue - the U.S. Constitution. There is much going around the internet, and by email, regarding Obama's eligibility to be President based on any number of issues which most of you have already heard about so I won't mention them here because it's not pertinent to this blog. Many Americans are almost up in arms over the spending and government takeover of the automotive industry, the banks, the insurance industry, and of course healthcare. Presidential and Congressional spending is stratospheric! Mr. Obama is leading the way into accelerated change. Does America need this much changing? Why would a 48 year old man think that he knows best for 300,000,000 other Americans? Is he really off track with an unrecognizable leftist agenda or are many of us simply afraid of change? My main question to you is this; do you believe by his actions, his deeds, or in his words that Obama is acting within the guidelines of the United States Constitution?