-By Gregory Solman

LOS ANGELES Creative directors Mark Fitzloff and Susan Hoffman have been elevated to executive creative directors at Wieden + Kennedy. They will effectively be running the creative department at the Portland, Ore., headquarters of the independent shop., an agency representative confirmed.

Fitzloff and Hoffman replace Steve Luker and Jelly Helm, who took over lead creative roles at the end of 2006, a few months after Tom Blessington assumed Portland managerial duties from COO Dave Luhr, freeing him to concentrate on global network operations.

Neither Helm nor Luker will immediately exit Wieden.

Helm will return to supervision of Wieden's WK12 in-house advertising school, effectively exchanging positions with Hoffman. Luker is expected to meet with principal Dan Wieden this week to determine his future at the network.

Tensions within the senior creative ranks appear to be prompting the changes, according to sources.

Friction between Luker and Helm and Mike Folino, a key creative director who had worked on Nike, led to the latter's departure in March 2007, sources said. Former Nike global account director Rebecca Van Dyck also left for a global marketing position at Apple shortly after Luker and Helm took the creative reins at Wieden.

The executives involved either declined comment or could not be reached.