Labour leader Ed Miliband criticised the lack of investment in Watford General Hospital on a site visit this week.
He said a spending review is "urgently" required to future-proof the aging hospital.
Speaking at the hospital, Mr Miliband said: "The people of Watford have been let down.
"There has been poor investment.
"The Labour party is looking at a spending review for Watford General.
"I recognise the urgency with which that is required."
The leader of the opposition met with Samantha Jones, chief executive of the West Hertfordshire NHS Trust, as well as patients, their families and staff during the two-day tour.
Ms Jones, who has previously described Watford General’s buildings as "unfit for purpose", said she was delighted to facilitate Mr Miliband’s private visit.
She said the MP for Doncaster North was shown the hospital’s busy accident and emergency department, dementia unit and children’s ward.
Mr Miliband was also briefed on the challenges facing the hospital and NHS Trust.
He said the visit was an opportunity to see the "real pressures on hospital departments".
He said: "This hospital faces the challenge of modernisation in its infrustructure and buildings.
"It's been a long running challenge that needs to be looked at and addressed.
"I saw the maturnity service here and the birthing centre, which is in a new building. The building seems to have made a huge difference to the mums there.
"But other parts of the hospital are much more out of date and it impacts on the quality the patients have."
Watford Labour councillor Matt Turmaine joined Mr Miliband on his visit and spoke for the party on the proposed Health Campus development.
Plans, which include building hundreds of new homes and car parking facilities, while leaving space for new hospital buildings have proved contentious.
Plot holders at the Farm Terrace Allotments, the land of which would be included in the campus, have lodged a legal challenge claiming they were "misled" about the amount of private development in the proposals.
Mr Turmaine said the people of Watford need to know in "concrete terms" what parts of the touted plans are going ahead.
The representative for Holywell Ward said: "We have campaigned to support the allotment holders.
"There’s still a query over whether the allotment land will be need to be used as hospital carparking.
"Watford General has been in need of investment for a decade now.
"There needs to be a commitment to patients."