More than two thousand people have signed a petition opposing the merger.
But after Guardian Angel opposed the merger, the final decision was made.
"We will oppose the merger with every resource available to us."
Morris opposed the merger, and had for some time been campaigning to establish the institute as a university in its own right.
The approval has never been in much doubt - all five commissioners have made it clear that they do not oppose the merger.
A group opposing the merger said it would appeal.
That broad reach has led consumer advocates to oppose the merger strongly.
Senator Biden said in an interview that he was inclined to oppose the merger.
Newspaper employee unions, which opposed the merger, welcomed the decision.
The Spanish Government is not expected to oppose the merger, bank executives said.