Q:

How can I tackle being retroactively assigned project ownership for blame? 

I have a situation where, in spite of not being the project lead, I've been expected to do most of the project work, but without the necessary support and timely input from colleagues. 
Much of the work is of a technical nature, providing specifications and detailed information on our systems, but I've been brushed off, priority around tasks on the project is constantly pushed out for other work and responses have taken ages to come through.  Emails often go unanswered for weeks despite repeated follow-ups. 
As a result, the project has dragged on well beyond the expected completion date. 
I feel that project ownership is being retroactively assigned to me because no one wants to take responsibility for the information provided and that there is someone to blame for the delay.  What can I do to address this?  Is there a effective way that, without just trying to pass the buck, I can tackle this ambiguity around the roles and responsibility in the project and deal with this lack of urgency? 

A:

Speak to your manager and explain the situation. 
You've been left with a huge amount of work with no clear direction or goal, and not much in the way of accountability. 
Your manager needs to know how much of your time is being sucked up in this, and as a consequence how much time/money is being wasted on wild goose chases. 
Raise this as a concern with your manager and ask how you should proceed. 
Personally, I'd recommend shelving the project until it can be rebooted with some decent leadership and management.   From what you're saying, it seems as though no one is invested enough to see it succeed (and therefore, what practical use has this project got?)