Health Secretary Jeremy Hunt has ordered an investigation into the decision to close Grantham's A&E services overnight.
The Grantham and District Hospital unit began closing early in August in a trial expected to last three months.
But a shortage of A&E doctors has forced United Lincolnshire Hospitals NHS Trust (ULHT) to keep it closed.
Lincolnshire county councillor Christine Talbot she was "delighted" the decision will be reviewed.
The county council's health scrutiny committee voted to refer the decision to shut the unit overnight to Mr Hunt in November.
On Wednesday, Mr Hunt wrote to committee chairwoman Mrs Talbot to say the matter had been passed to the Independent Reconfiguration Panel (IRP) for review.
She said: "When we referred the issue to the Secretary we did not believe that overnight services would be reinstated in February as planned, and those fears proved to be well-founded.
"I'm confident that the IRP will agree that a full review is warranted, and I look forward to being able to present our case in full.
"ULHT need to realise that the people of Grantham deserve better. I hope today's decision will underline that this is not something we will let rest."
Mr Hunt has asked the IRP to present its initial assessment of whether a full review is necessary by 22 March.
Speaking earlier this month, Dr Suneil Kapadia, medical director at ULHT, said the trust is committed to reopening the unit at night and is trying to recruit staff.
ULHT employs about 17 doctors across its three sites in Lincoln, Boston and Grantham, and needs a minimum of 21 to keep all of them open for 24 hours.