Shadow health secretary Jon Ashworth has told Prime Minister Theresa May to "get a grip" after the maximum time patients have to wait for referrals of 18 weeks was increased.
The NHS have failed to meet its target of seeing 92% of patients within 18 weeks since February 2016. Ashworth believes the collapse in the ability to fulfil that target could be illegal, as the service has declined from being "pushed back to the bad old days" due to "severe Tory under-funding" on the NHS.
"My worry about the dropping of this 18-week target is – this isn't a promise by politicians or a promise by NHS bosses. It is actually enshrined in the NHS constitution," he said, speaking to Sophy Ridge on Sunday.
"Parliament legislated for that – it is an absolute right of patients to be seen within 18 weeks."
Ashworth confirmed he will quiz the Health Secretary Jeremy Hunt on the legality of his actions and called on more funding to be provided for the NHS.
"Today I am writing to Jeremy Hunt asking him to publish what legal advice he may have on this, asking him whether he is going to come to parliament and legislate to change the NHS constitution.
"If he's not, he is breaking that constitution – he's breaking the rules – and then he has to go to the chancellor and ask for the funding so we can get an NHS that we expect."
He continued: "It is absolutely disgraceful that pensioners, elderly people, are going to be waiting longer for their hip replacement, knee replacement, cataract replacement – operations of that order.
"What is going on in the NHS really is a crisis and Theresa May's got to get a grip."
NHS Chief Executive Simons Stevens claimed plans were in place to install 150 new urgent treatment centres as alternative options to A&E and freeing up to 3,000 hospital beds by extending GP services.