The government has refused to guarantee its 100,000-a-day coronavirus test target will definitely happen.
Health Secretary Matt Hancock last night pledged to ramp up tests to hit the target by the end of April.
But today he refused to guarantee it will happen, saying it is only a "plan" and a "goal".
And he refused to say he will resign if there aren't 100,000 a tests by May. He told LBC radio: "It's much more than about that. It's about getting the country out of this situation we're in."
Mr Hancock also clarified his 100,000 target might include both swab tests - which show if you currently have the virus - and antibody tests which show if you might be immune.
That means it can't be compared to the previous target of 25,000 tests a day - which only included swab tests.
Antibody tests are useful but not a single one has been approved yet; may only work 28 days or more after infection; and aren't needed as urgently as swab tests.
There are 3,500 antibody tests a week taking place for research purposes at the government's facility Porton Down, but not in the wider community.
Shadow Chancellor John McDonnell said “we need more details” of how the 100,000-a-day pledge will be met.
He told the BBC a breakdown of the figure was needed to clarify “confusion” about whether there is a reliable antibody test.
No antibody test has yet been approved for use in the UK, despite millions being provisionally ordered.
Mr Hancock today admitted the government has not yet found a single antibody test that works.
He confessed a number of antibody tests had failed to get approval - with one misdiagnosing three out of four cases.
Today he faced scrutiny over how the 100,000-a-day target will be met.
BBC Breakfast asked him: "Can you guarantee this is going to happen?"
He replied: “Yes, it’s got to happen”
The presenter cut in: "No, it’s *going* to happen?"
Mr Hancock said: “I’ve got a plan to get us there. I’ve set it as a goal.”
The Health Secretary refused to give a guarantee because he said there were many “pieces of this puzzle”.
His "five pillars" to ramp up testing include the NHS, existing tech companies, new companies and university labs.
He said: “There’s an awful lot of work to do to make it happen. That’s why I talk in the language of a goal. Of course we’ve got to get there, but there’s a huge amount of work to do.”
He added: "There are barriers, there will be bumps in the road, and some of this is going to be very difficult."
Mr Hancock also faced anger over the fact just 5,000 NHS staff have been tested for the virus.
Today he insisted only around 35,000 frontline NHS staff are not in work due to coronavirus - far lower than figures over 100,000 that have been reported.
And he said the number of NHS staff tests would ramp up "very quickly".
But again, he could not guarantee when all NHS staff will get the tests they need.
He said he hoped for it in the coming weeks but added: "I don’t want to make a commitment I can’t meet".
However, he insisted: "Money is no object here, what matters is getting the country out of this situation as quickly as possible.
"The historians can crawl over what we've done. All I can say is hand on heart at each stage I've done everything I possibly could, but then new ideas come in and new thoughts come forward."
Mr Hancock said the peak of the virus may be “slightly sooner” than previously predicted, “in the next few weeks”, now that lockdown measures have come into play.
However, the Health Secretary said it’s “very very sensitive to how closely people follow the social distancing guidance.”
Urging people to stay at home to keep the peak small, he told BBC Radio 4’s Today programme: “The more people follow those social distancing rules, the sooner that peak will be.”
