The US House of Representatives has passed a bill that would ban human cloning and sentence violators to prison and fines as high as $1m.
Lawmakers passed the bill in a 241-155 vote, rejecting some exceptions that would have helped researchers work towards cures for diseases such as Alzheimer's, Parkinson's and diabetes.
But the bill is expected to have a much tougher time when it goes before the Senate.
The House passed a similar bill in July 2001 by 265-162, but it stalled in the Senate.
We can no longer wait for another biotech company to claim they have cloned children
The new bill, introduced by a cross-party coalition of senators, reflects the Bush administration's stance that all human cloning research must be banned. It argues a cloned embryo is a human even before implantation in a womb, and to destroy it for research would be immoral.
It also comes after a company claimed last year to have cloned the first human baby. Clonaid's claim was never verified.
Republican Representative Sue Myrick said anything other than a total ban "would license the most ghoulish and dangerous enterprise in human history."
"Congress must act now," she said. "We can no longer wait for another biotech company to claim they have cloned children."
But Democrat James McGovern said the bill would "close the door to important research" using what is known as therapeutic cloning.
"I can't see how it is moral to look in the eyes of someone with Alzheimer's or Parkinson's and say we're going to stand in the way," he said.
The Human Cloning Prohibition Act would make it a federal crime to perform human cloning to create a pregnancy or for medical research purposes, as well as to import a clone human embryo or product derived from one.
It would impose a $1 million fine and up to a 10-year prison sentence for violators.
President Bush praised the House of Representatives for approving the bill.
"Like all Americans, I believe human cloning is deeply troubling," he said, in a statement.