The Caleb Porter era is over in Portland.

In a shocking move, Porter has stepped down as head coach of the Portland Timbers, a source confirmed to the Oregonian/OregonLive Thursday.

Porter's surprise departure comes after a successful 2017 season where the Timbers finished first in the Western Conference before being eliminated in the Western Conference semifinal round of the MLS Cup Playoffs.

During his five years with the Timbers, Porter compiled a 68-50-52 record, led the Timbers to two first-place finishes in the Western Conference and won the 2015 MLS Cup.

Porter originally joined the Timbers ahead of the 2013 season after the club fired former head coach John Spencer.

Porter, who arrived in Portland after a successful tenure at the University of Akron, immediately turned the club around, leading the Timbers to a first-place finish in the Western Conference and the Western Conference Championship series in the MLS Cup Playoffs in his first year in Portland.

The Timbers made the decision to sign Porter to a long-term contract extension in January 2016, months after Porter led the Timbers to the 2015 MLS Cup title. But the two sides made the decision to part ways at Porter's request this week.

It was not immediately clear where Porter's next destination would be or whether he had a new job lined up. It is likely that other teams in MLS would be interested in Porter's services. His name has also been floated as a potential candidate for the U.S. Men's National Team coaching job.

The Timbers are expected to formally announce Porter's departure Friday. Naming a new head coach will now become Portland's top priority for the offseason.

Porter did not immediately respond to requests for comment Thursday night.

-- Jamie Goldberg | jgoldberg@oregonian.com

503-853-3761 | @jamiebgoldberg