H1B Extension Using Existing 140 From Another Employer

Guys,

Please bear with me for posting this question here but your guidance to my current situation is much required.

My 2nd H1-B extension completes on Sept 30th -2012 and I am up for another Three Year extension based on the I-140 approved (PD July-2010 :o) with my current Employer A .

If in any event my H1-B extension gets rejected with my current employer, I am planning to apply for an extension through one the clients that I previously worked with.

So in such scenario will this client ( Employer B) be eligible to file for three year H1-B for me based on a I-140 that is held/owned by Employer A?

Appreciate your advice in this matter.

Regards,

Prabhas