about passive voice

I've got some problem with the pairs of changes below.
They're kinda confusing to me.
Please help analyse it.
Thanks a lot.

1)
Active:
There is a great possibility that Mr. Wong will resign next month.
Passive:
Mr. Wong is believed to be going to resign next month.

Can I change that into this instead?
Mr. Wong is believed to be resigning next month.

2)
Active:

It's likely that they will call a strike for tomorrow.
Passive:
The strike is expected to be called for tomorrow.

In both pairs, the clauses in the original sentences are in future sipmle.
So, if the change in 1 is correct, should 2 be changed into:
The strike is expected to be going to call for tomorrow.
Why is there such a difference between 1 and 2?

thank you very much

[Tdol]

1) Mr. Wong is believed to be resigning next month.
This sounds much more natural than the version with 'going to',which sounds clumsy to me.

2) Here we don't need the 'goingto' again. The time is obvious and we can use the infinitve to express the future without addingit.