The 30-year old USA international has flown to London to put the finishing touches on a two-month agreement as the Cottagers strive to climb out of the relegation zone.
Dempsey was a star for Fulham prior to his 2012 move to Tottenham which preceded a lucrative shift back to his homeland with the Sounders in in August this year.
Dempsey has a clause in contract allowing him to go on loan from January 1 until the end of February and Sounders general manager Adrian Hanauer is fairly certain that passage will be activated.
"And Clint did have something in his contract that would allow him to go on loan for the first couple of months here," he said.
"Obviously the rumors are pretty rampant, and I think it's likely, but until it's done, we won't report it as done. But I do think it's likely."
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