Convince employer to start GC processing immediately to port priority date

Hi All!

I have my I140 approved with previous employer.

I accepted full time position with Client where I was working with previous employer. I clarified with them that my priority date needs to be ported ASAP.

Before joining they said yes.

But now they are saying they would start GC processing next year.

I asked for call with Attoreny.

How should I present my case to convince my employer that GC processing needs to be started immediately?

I was thinking following :-

  1. Porting Priority Date

  2. What if Priority date becomes current next month. I won’t be able to file for I485 as I no longer work for previous employer

  3. Why keep dependency with previous employer.

But couldn’t find any more reasons. Could you think of any other reason which Employer can not deny?

Thank you for your help!