No one is a Labour parliamentary candidate until approved as such by that party's National Executive Committee. That Committee now has a pro-Corbyn majority, and ought therefore to resolve that it will never, under any circumstances, approve the parliamentary candidacy of Tony Blair.
Blair then needs to be asked live on air whether he would ever seek election as anything other than an official Labour Party candidate. That is a Yes-No question, and any answer other than No is automatically expulsionable from the party, with a five year ban from even so much as applying to re-join.
While the NEC was about it, then it ought to suspend the membership at least of those Durham County Councillors who presented themselves in order to vote against the Teaching Assistants. Based on that, Windlestone Hall, the Cricket Club, and the cuts to transport provision, the Leader of the Council, Simon Henig, ought to be expelled forthwith, and therefore made subject to the five year ban. The forfeiture of his CBE ought also to be explored most actively. Let's face it, that would save time.
Being suspended or expelled, those people could not be Labour candidates in May, thereby potentially saving the party dozens of seats that such candidates would certainly have lost. The Teaching Assistants, being council employees, cannot be council candidates. But their supporters include many people who not only could be, but in several cases should have been years ago.
The NEC can grant membership and candidacy on the spot in emergencies, and this is an emergency. Alternatively, it can watch the devastation of the largest Labour Group in local government, taking the authority to No Overall Control while at least depriving the Leader of his seat before he lost his liberty. Of course, as supporters of Jeremy Corbyn, the majority of the NEC's members may actively wish to see that outcome.