Alastair Stewart: This could prove to be a defining week for Boris Johnson

This could prove to be a defining week for Boris Johnson, his government and the Conservative Party.

The issue is settling, once and for all - as the PM puts it - the crisis in social care funding.

It was in his 2019 manifesto and in his 'steps of Downing Street' speech when he took office.

Unfortunately for him, there was another pledge in his 2019 manifesto: "We promise not to raise tax, National Insurance or VAT".

There's a continuing debate at the highest levels of Government - involving the PM, his Chancellor and his Health & Care Secretary over whether there should be a 1%, 1.5% or even 2% rise in National Insurance to fund care and help the NHS clear the post-coronavirus waiting list crisis.

It is understood they are trying to cut a deal right now.

On Monday the Chancellor talks to the 1922 group of back bench Tories.

On Tuesday there's Cabinet where Johnson hopes the matter can be settled.

But there's also briefing in many newspapers this morning of a re-shuffle on Thursday!

A warning shot across the bows of Tory rebels or an attempt at a fresh start?

For many Tories, it all speaks to an existential crisis for the Party.

An unnamed Minister is reported as saying any rise in NI or tax to pay for social care would be "morally, economically and politically wrong".

Marcus Fysh, Chair of the Economic Growth group of Tory MPs writes "I do not believe it is correct to be taking a 'socialist' approach to care when private insurance and other contribution schemes have not been set out'.

And former Minister Steve Baker says "We need a fundamental review of what the state does and how it's funded"

In short, the charge sheet against the PM is that he is a promise breaking, tax-raising, big state Tory - it has all infuriated a growing number on his own side: they simply don't want it.

As Iain Duncan Smith warns it will take the tax to its highest level since Labour's Clement Attlee's welfare state government of the 1940s, a former unnamed Cabinet Minister says 'if you want to take that road, call an election'.

But it all plays to Labour's advantage: Shadow Treasury Minister Bridget Phillipson says the Tories are heading for a hat-trick of broken promises: foreign aid, the triple lock on the state pension and now raising NI to pay for care.