Sorry if I caused any confusion...I meant to say that so many are here on visa's and manage to obtain some kind of visa until they get a perminent status. Although it isn't always easy, it can be done since thousands manage to do so.
You can try what some have stated, but so far I never heard that it was possible. As far as I know you have to be a citizen to sponsor any one else and as far as I know no GC holder can sponsor any one...no child, no wife, etc...JMO! But it won't harm you to call a immigration lawyer and ask the question. Maybe they will have a free phone consult...
The visa bulletin provides some answers:
FAMILY-SPONSORED PREFERENCES
First: Unmarried Sons and Daughters of Citizens: 23,400 plus any numbers not required for fourth preference.
Second: Spouses and Children, and Unmarried Sons and Daughters of Permanent Residents: 114,200, plus the number (if any) by which the worldwide family preference level exceeds 226,000, and any unused first preference numbers:
A. Spouses and Children: 77% of the overall second preference limitation, of which 75% are exempt from the per-country limit;
B. Unmarried Sons and Daughters (21 years of age or older): 23% of the overall second preference limitation.
Third: Married Sons and Daughters of Citizens: 23,400, plus any numbers not required by first and second preferences.
Fourth: Brothers and Sisters of Adult Citizens: 65,000, plus any numbers not required by first three preferences.
So, yes, a PR can sponsor a spouse but if you look further down, the cut-off time is about 4 years so either way it will take a while (it seems US citizens follow a different process for spouses and children under 21, all of which is much quicker). You can sponsor as a PR, or wait to become a US citizen - either way it will take a while.
Sensible advice from Bentlebee above is to consult a lawyer - I am sure our host on this forum would appreciate that
Also, Wikipedia is extremely informative as well.