In a statement Thursday, Hanauer said the Sounders hope to have the transaction completed in the next few days.
Montero has been with Seattle since its first game as an expansion franchise in 2009. He's the club's all-time leading scorer with 60 goals and 43 assists in 160 games. But Montero has not played well in the MLS playoffs.
On his Twitter account Wednesday, Montero posted a note thanking Seattle's fans and the organization, saying, "I will be back one day."
The loan would leave two designated players on Seattle's roster: midfielders Mauro Rosales and Christian Tiffert.
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