The health minister is to make a statement after calls for her resignation amid claims an independent report on changes to the NHS in Wales was unfairly influenced by civil servants.
Emails show independent academic Marcus Longley in contact with civil servants asking them for information to support reforms his report proposed.
The Conservatives say the author was pressured to support certain changes.
Prof Longley and the Welsh government insist the report was independent.
How damaging is this?
It is absolutely damaging for a few reasons.
Firstly, the opposition parties, they are as one over this, something we've not seen much of during this term.
They think it's serious, they're not going to let this go so the Welsh government can't simply peel off one party if you like and accuse them of making trouble.
Secondly, there are few areas, if any, of policy-making in Welsh terms that have proved to be more sensitive and difficult over the years than health.
Here we are again with some fundamental reforms planned. The Welsh government, officials and NHS experts are aware, I think, that the key to that is trust and that's again why I think this is damaging.
They're perfectly aware that when there's talk of changes to local service provision - in other words to people's local hospitals - people tend to resist and they need to be persuaded that change is right and necessary and the argument that I've heard is that maybe politicians aren't the right people to make the case for change.
You need medics, you need experts, independent experts in the medical field to make the case and that is why that words "independent" and "non-partisan" have been so key in the way the report has been presented to the public.
But Prof Marcus Longley said he went to the Welsh government for data?
There is absolutely no problem in asking for data. He makes the point that they hold the data and he needs it, so he asked for it. The key issue here is that he has to be seen as an independent expert sifting through all the data and coming to a conclusion and not someone who was searching for bits of data - and that is what the opposition parties are pointing to in these e-mails.
For instance, in one e-mail in February, Professor Longley seems to be expressing concern to government officials that he doesn't have enough data to prove that services need to be overhauled.
As we've discussed, a crucial piece in the jigsaw - the argument we can't stay as we are, just look at the outcomes, so far, so elusive.
In another he says that the evidence as presented doesn't seem to be incisive as we might have hoped. Now then if the "we" is Prof Longley and his team, the "hoped" would be problematic for him in that sentence.
If it's "we" as Prof Longley and government officials and NHS officials then clearly that is very difficult for them both.
In the next paragraph he asks for more evidence to "sharpen up the document and its impact in supporting the case for change.
In another the head of the NHS in Wales - who bear in mind is a Welsh government official, there is no great dividing line here between the NHS and the government - asks Prof Longley to ensure the report has a more positive bent and "set out the case for change".
So what the opposition parties are saying is that this isn't simply the bald exchange of data; they would have no problem with that.
What they do have a problem with is what they say very clearly seems to be - "conniving", "sexing up". They are comparing it to sexing up the Iraq document under a previous UK Labour government.
Where does this go now?
Elin Jones from Plaid Cymru had called for an urgent statement from the minister. Lesley Griffiths said she would be making one to assembly members later on Tuesday.
Plaid Cymru are saying either assembly members have been deliberately misled, as have the public or the government was somehow unaware of the meials. Either way says Elin Jones this is serious and damning.
Kirsty Williams is talking of the public being "insulted" with that word "independent".
The Welsh government says its officials simply responded to requests for data and other information and that there was no attempt at all to "influence or amend" the report.
I think it is inevitable on a day when assembly members will be in Cardiff, will be in the chamber, that the opposition parties will make absolutely certain that this is raised today in the assembly chamber and Lesley Griffiths is the one they want to hear answering questions.