A judge will decide on Thursday over objections from Dutch shareholders' group VEB to the $21 billion sale of the unit to Bank of America. The shareholders claim that a sale of such a size needs their approval.
It is thought that if the LaSalle sale is derailed then the proposed â¬65 billion takeover of ABN by Barclays or one of the other suitors could also be held back.
At the end of last week a group headed by Royal Bank of Scotland, Santander and Fortis revealed that they were ready to make an offer up to â¬72 billion for ABN. However if Chicago-based LaSalle is sold the rival bid move may be scuppered.
VEB has described the sale of LaSalle as the 'poison pill' that could put off any other bidders for ABN besides Barclays.