Can Obama make a change in the way green cards are counted?
No. The Immigration and Naturalization Act (INA), the body of law governing current immigration policy, provides for an annual worldwide limit of 675,000 (480,000 Family + 140,000 employment + 55,000 Diversity) permanent immigrants, with certain exceptions for close family members for U.S. citizens.
If he does it, the annual worldwide limit of permanent immigrants will be over 675,000.
By looking at the whole effect, if the President issues executive orders for changing in the way green cards are counted, he is setting up a NEW annual worldwide limit on green cards
The U.S. constitution has CLEARLY defined that set up the annual worldwide limit on green cards are the duty of the U.S. Congress. SO LET THE CONGRESS DO ITS JOBS.