This is really nothing more than a matter of economics. We already cannot really afford Medicaid as it is, so by expanding it, one or two things will happen. We will either go completely bankrupt as a nation by trying to pay for it, or service will have to be lowered.
It's simple, the more people who have health insurance, the more doctors there will be, given the incentive stays the same. The more doctors and clinics there are, the more accessible health care will be to everyone. There are tons of people out there who just plain can't afford to go to a doctor. That is absolutely wrong in a nation such as this.
I don't see why it would lower access to Medicaid. As long as the costs of the program are covered, there shouldn't be any trouble. I've yet to hear any reasons suggesting that expanding Medicaid will make it unavailable to people who need it. Besides, there's plenty of money available to cover the costs.
No, I do not believe that Obama's efforts to expand Medicaid in the states will lower access to healthcare. In fact, I believe it will do the opposite. There are many people in this country who are either uninsured or under-insured for various reasons and this will qualify more people for the healthcare that all humans in this country deserve.