Wes Streeting MP, Shadow Health and Social Care Secretary, and Stockton North MP Alex Cunningham visited the University Hospital of North Tees on Friday.
They toured its breast cancer unit and met with NHS trust leaders.
Mr Streeting criticised “mismanagement” of the NHS by the Government as latest figures show there were 57,000 people on the waiting lists at South Tees and North Tees and Hartlepool NHS Trusts at the end of December.
Also 1,600 people have been waiting for more than a year for treatment and 6,000 people are waiting for cancer tests and scans.
Mr Streeting said: “After a decade of Tory mismanagement, the NHS went into the pandemic with record waiting lists and staff shortages of 100,000.
"It’s not just that the Tories didn’t fix the roof when the sun was shining, they dismantled the roof and removed the floorboards.
“The Conservatives are so incompetent they’ve come up with a plan that sees patients paying more in tax but waiting longer for care.”
He said a Labour government would reduce waiting times and provide the NHS with the staff it needs to treat patients on time.
The Government has said it aims to tackle the backlog of the pandemic through a series of measures in its Elective Recovery Plan.
It includes “record investment” to deliver nine million more treatments, scans and operations by 2024.
The aim is that nobody waits longer than a year for surgery by March 2025.