Geddes, 55, is the longest-serving pro tem in Idaho history and his announcement sets up prospects of a wholesale shift in leadership among majority Republicans.
At least two of the four leadership positions were already being contested at next week's organizational session. Geddes' decision ensures that at least three spots will be in play and raises the prospect of all four leadership posts changing. With four freshman Republican senators replacing less conservative predecessors, the more moderate Senate is edging closer to the more conservative House. How that will play out in leadership races is unclear.
Two candidates immediately emerged to succeed Geddes, Senate GOP Caucus Chairman Russ Fulcher of Meridian and Senate Local Government and Taxation Chairman Brent Hill of Rexburg.
Fulcher announced his candidacy in an e-mail to colleagues shortly after 10 a.m. Monday. Hill later told the Statesman he is running.
Other possible successors were thought to include: the No. 2 in GOP leadership, Majority Leader Bart Davis of Idaho Falls; Senate Finance Committee Chairman Dean Cameron of Rupert; Senate Judiciary Committee Chairman Denton Darrington of Declo; and three-term Sen. Jeff Siddoway of Terreton.
Cameron said Monday afternoon that he will remain chairman of the Finance Committee, as the state wrestles with huge budget problems.
Geddes, Soda Springs, had hoped to keep the news quiet until Wednesday, when the weekly newspapers in his Southeast Idaho district publish.
He e-mailed an embargoed news release to his Senate colleagues and staff about 8 a.m. Monday, asking that the news not be spread until Wednesday.
But Cameron broke the news shortly after 10 a.m. on Twitter, writing, "Shocked today! PresProTem Geddes announces he's not running for ProTem. He has served very well & big shoes 4 his successor."
Cameron said he didn't realize Geddes had asked for an embargo and had heard the news from a colleague. He then spoke with Geddes, posting his tweet before he read the news release.
Geddes told the Statesman he decided it was time to step down in advance of the Legislature's organizational session, Dec. 1-2.
"It's not a job you get tired of, but you may get tired," Geddes said.
Geddes will remain in the Senate, where he has served 16 years.
Geddes also said that if the embargo was broken, he understood that other media would run the story.
His news release follows:
"The President Pro Tempore of the Idaho State Senate is a bi-partisan position that is elected by all serving Senators. I was first elected to that position in 2000 and have now served in that capacity for 10 years, the longest ever in Idaho’s history. It has been an incredible experience and one that I have truly honored and enjoyed. I have served in leadership with legislative members that I absolutely respect and admire. I have also had the honor of working closely with House Speakers Newcomb and Denney; Governors Batt, Kempthorne, Risch and Otter and their respective administrations.
I will not seek re-election for Senate leadership during the 2010 Reorganizational Session that will be held in Boise on December 1-2.
I am elected to continue serving in the Idaho State Senate and I will continue to represent the citizens of District 31 in that capacity.
I wish to express my sincere thanks to each and every Senator that I have and will continue to serve with, as well as the citizens of our great state. I have enjoyed tremendous support, experiences and the opportunities that fulfilling the responsibilities of President Pro Tempore in the Idaho State Senate provides.
I have worked with a wonderful group of Senate and state employees who support the legislative process and enhance openness and access to government. I want to thank each of them for their dedicated service.
Most of all, I express thanks to my wife Tammy and family for allowing me time and support necessary to serve in this leadership capacity."
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