"It's not perfect," he said. "My decision has been based from the very beginning on the substance of this policy."
Boyd said he wanted the bill to be deficit-neutral, bring down increasing health care costs, improve coverage and allow patients to choose their insurers.
Boyd is one of the most conservative Democrats in the House. He supported, for example, President Bush's plan to privatize Social Security in 2005.
He's been facing a tough primary from a state senator, Al Lawson, who has attacked him for his conservative stance. He's also been bombarded with lobbying efforts and ads from both sides of the debate.