Obama endorses civil unions but not gay marriage. The president has said his views on the issue are evolving and that decisions on marriage should be left to the states.
As many as 600 guests will pay up to 35,800 to attend the campaign fundraiser.
New York's Republican Senate plans to consider a gay marriage bill in a closed-door session on Thursday.
The bill will either be sent to the Senate floor for a vote or held back, effectively killing the measure for the second time since 2009.
The measure that has pushed New York to the center of the national gay marriage debate appears to be one vote shy of passage if it gets to the floor.
The Democrat-led Assembly has already supported the bill.
The Associated Press contributed to this report.
