BUFFALO, N.Y. -- First, the good news: According to Dr. Nancy Nielsen, the Senate's health care bill is a better plan than the one rolled out by the House -- minimally.

"It gives more generous tax credits to those who need them, and the tax credits are tied to the person's income, not their age," said Nielson, senior associate dean for health policy at the University at Buffalo's Jacobs School of Medicine and Biomedical Sciences.

The bad news: "It's much, much worse in terms of what it does to Medicaid. Much, much worse," Nielsen said.

Nielsen was the president of the American Medical Association at the time the Affordable Care Act was debated. She says the two groups that will be hit hardest by this plan are those on Medicaid -- slated for major cuts -- and those who are insured through the marketplace.

The big shift there is that states would be able to opt out of the essential health benefits package.

"Hospitalization, drug coverage, maternity coverage. You start having states eliminate that, and people with pre-existing conditions are going to have a hard time," said Nielsen.

One organization that will have a hard time if the bill passes without changes is Planned Parenthood.

"This bill is the worst bill for women in a generation," said Betty DeFazio, executive director of the Planned Parenthood of CNY & WNY Action Fund.

The slashes to Medicaid would defund the group. DeFazio says this doesn't mean locations would have to close their doors, but it would be harder for some to access services since 60 percent of its patients nationwide are Medicaid recipients.

"Patients on Medicaid would no longer be able to come to Planned Parenthood for their care," she said. "It really is going to impact how the most vulnerable in our communities are going to be able to get essential health care.

Nielsen says people will lose coverage under this plan, but it won't be clear how many until the Congressional Budget Office releases its assessment.