Federal legislators urged the Sierra Club not to delay the Tahoe Regional Planning Agency’s Regional Plan Update prior to the environmental group’s challenge to the wide-ranging plan this week.The existence of the TRPA, as well as millions of dollars in federal funding, could be jeopardized by delays in implementation of the RPU, according to a Feb. 1 letter to the Sierra Club from U.S. Sens. Harry Reid and Dianne Feinstein.The Sierra Club and Friends of the West Shore filed a lawsuit to stop implementation of the TRPA’s RPU in federal court on Monday. The TRPA passed the plan regulating land …