More people are enrolling in Medicaid rather than in private insurance plans, leading critics of Obamacare to charge that the federal government will end up playing a much bigger role in the nation's healthcare system than had been expected.Medicaid expansion always was expected to be a major part of bringing health coverage to the uninsured, reports The Wall Street Journal. The state reports are seen as good news for Obamacare advocates who said the law would bring health insurance to even more Americans.According to the Congressional Budget Office, 9 million people were expected to sign up for Medicaid in 2014, and 7 million were expected to sign up for private coverage.But the Obamacare website's ongoing problems are slowing the number of people able to sign up for private plans.No figures are available for Medicaid expansion in the 36 states where people are being enrolled through the troubled federal HealthCare.gov website. But in states which have set up their own exchanges under Obamacare, Medicaid enrollment is booming.In Kentucky, for example, 82 percent, or 21,342, of those enrolling in new insurance plans under Obamacare are signing up for Medicaid, the Journal reported. In Washington, it's 87 percent of 35,528; and in New York, 64 percent of some 37,000.Part of the growth is because states are reaching out to people who already receive federal benefits such as food stamps, said Matt Salo, executive director of the National Association of Medicaid Directors.Under Obamacare, Medicaid is available for people who earn up to 133 percent of the federal poverty level, making many more people eligible.In addition, it's easier to get Medicaid than private coverage in many cases. Enrollees can go to local offices to sign up for coverage, rather than having to depend on the glitch-prone Obamacare website.But there are concerns that Medicaid will draw more young people who could have bought private insurance coverage, which could drive up the cost of private insurance for older, sicker individuals. Obamacare was designed, in part, to rely on younger people signing up to help offset or drive down the costs of insuring older people.Drew Gonshorowski, a policy analyst with the Heritage Foundation, says increased Medicaid sign-ups among young people could throw a wrench into Obamacare's affordability argument."They need young, healthy individuals to support them so premiums don't go up next year," he told the Journal.The Cato Institute's Michael Cannon agreed, telling Fox News , "There are a lot of elements of this law that have to work, that must work. Otherwise the whole thing collapses. They need — need — lots of healthy people to sign up for insurance through the exchanges."There's also concern that Medicaid expansion may result in a shortage of doctors that could leave many newly insured seeking care in a two-tiered system in which they will have access to less-experienced medical staff, longer travel times to find a doctor who accepts Medicaid, and could wait weeks longer for appointments than people with private coverage.Still, there are those who say it's too early to tell how increased Medicaid enrollment will impact Obamcare overall."This is a six-month open-enrollment period, so I think it's way too early to know now how many people are going to purchase coverage through these marketplaces," Robert Zirkelbach, spokesman for America's Health Insurance Plans, told Fox News "It doesn't feel like it, but we're only in week four now."