Helped by a marathon speech, Texas Democrats have managed to block a bill that would shut most of the abortion clinics in the state.
Democratic state Senator Wendy Davis spoke for more than 10 hours, in a stalling speech known as a filibuster, at the state capitol in Austin.
Republicans then scrambled to pass the bill, but the vote was ruled too late for a midnight deadline.
The bill would ban abortions after 20 weeks of pregnancy.
It would also require all pregnancy terminations to take place in surgical centres. The future of the legislation is now uncertain.
Bathroom breaks banned
The proposal, already passed by the Texas House of Representatives, was debated in the state Senate on Tuesday.
During her filibuster, Sen Davis read testimony and messages from women and others opposing the legislation.
She also recited previously suggested changes to the bill and recounted her own life story.
Sen Davis was picked to lead the filibuster because she had her first child as a teenager and went on to graduate from Harvard Law School.
"I was a poor, uninsured woman, whose only care was provided through that facility. It was my medical home," said Sen Davis, 50.
Rules of the debate stipulated she must remain standing, not lean on her desk or take any breaks, even for meals or to use the bathroom.
Republicans watched for any slip-up that would allow them to end the filibuster.
Supporters of the bill protested at one point that Sen Davis had received help from another lawmaker in adjusting a supportive back brace.
Texas Lieutenant Governor Dewhurst, who is Senate president, eventually suspended the filibuster after ruling that she had meandered off topic.
Democrats appealed that ruling, sparking a debate over parliamentary rules.
As the clock ticked to midnight, Republicans rushed to hold a vote on the bill, amid jeers from pro-choice protesters in the public gallery.
"Get them out!" Republican Senator Donna Campbell shouted to a security guard. "Time is running out."
But amid the disruption, Lt Gov Dewhurst said he had been unable to sign the bill within deadline following a 19-10 vote. He blamed an "unruly mob" in the gallery.
He reportedly hinted that the vote could be held again at a second special session.
Supporters of the bill say the measures will improve safety standards. It requires doctors who perform abortions to have admitting privileges at a nearby hospital.
The new law would mean only five of Texas' 42 abortion clinics would be able to remain in operation.
But opponents say this would force women to travel hundreds of miles or resort to dangerous methods to obtain a procedure.
The US Supreme Court legalised abortion nationwide in 1973, but about a dozen conservative states have enacted laws in recent years that seek to limit the procedure.
In March, North Dakota banned abortions once a foetal heartbeat is detected - as early as six weeks - in the most restrictive law of its kind in the US.
Earlier this month, the Republican-controlled US House of Representatives in Washington DC passed a bill banning abortions 20 weeks after fertilisation.
But the measure is unlikely to become law because Democrats control the US Senate and the White House.