In prepared remarks, Snowe urged "the president and Democratic congressional leaders to swiftly reject job-killing tax increases in these uncertain economic times, and allow a vote on legislation to extend all of the 2001 and 2003 tax relief set to expire on December 31."
Snowe's disapproval of the Democratic plan could mean that liberal leaders fail in getting the 60 votes needed to pass the president's plan.
Senate Majority Leader Harry Reid (D-Nev.) has signaled that he will put forward a bill that only extends the middle-class tax cuts. Earlier today, his spokesperson said the legislation will succeed only if it finds Republican support.
Snowe has been a key vote in passing legislation in the past and was considered one of the more likely Republican members to support Obama's tax plan.
Sources tell The Hill that is unlikely for Sens. Susan Collins (R-Maine) or George Voinovich (R-Ohio) to support the Democratic plan either.
It is unclear if Sen. Scott Brown (R-Mass.) will support the measure.