Of the 39 Senate seats, seven are awarded by President Nursultan Nazarbaev. Each of Kazakhstan's 14 regions has two deputies. The two largest cities -- Almaty and the capital Astana -- also have two each. It falls to regional and local officials to choose who will fill those 32 seats.
Senate elections rotate. Every three years, half the seats are up for new candidates, meaning this year only 16 deputies will be selected. Forty-one candidates were registered to participate in the selection process. Of them, 21 of them are from Otan.
Otan already has a majority in the Mazhilis, the lower house of parliament, and seems sure to have a majority in the upper house. Otan's dominance may play a key role in determining if Kazakhstan will next hold presidential elections in December 2006, as currently scheduled, or schedule an early vote ahead of January 2006, when Nazarbaev's term expires.
The outcome could make a big difference in whether the opposition is able to front a candidate who is able to present a realistic challenge to Nazarbaev, who has no term limit.
Some in Otan have already called for early presidential elections. Perhaps for this reason, the Senate selection has piqued the interest of politics-watchers outside Kazakhstan. For the first time, according to Lazzat Suleimen, a member of the Kazakh Central Election Commission, international observers will be on hand to watch the selection process.
"International observers have expressed great interest in elections to the Senate," Suleimen said. "The Central Election Commission has registered 52 observers. The majority of them are from CIS countries."
So international observers will be watching -- but, by contrast, there will be no Kazakh monitors. Dos Koshim is a longtime opposition activist and the head of the Independent Observers Network of Kazakhstan. He explained why his group is not interested in monitoring the Senate process.
"For five years we have stayed away from observing Senate elections," Koshim said. "The reason is because this chamber does not represent the people. That's why we refused."
According to Election Commission head Onalsyn Jumabekov, only two senators are not looking to return. One, Walikhan Kaisar from Karaganda, said he simply no longer wants to be a senator. The other, Zauresh Battalova, had her candidacy rejected due to incomplete documents.
Battalova was the only member of the Senate who represented an opposition view. She said the issue of the presidential elections has made the Senate selection a significant process both for international observers and for Nazarbaev -- who has final approval of all Senate members.
"The reason for the greater interest in these elections on the part of international observers can be explained by upcoming presidential elections," Battalova said. "The elections to the Senate are the last step before the presidential elections. It is clear that presidential elections will take place soon. That's why the international community is interested in these [Senate] elections."
Kazakhstan's Constitutional Council has repeatedly postponed a decision on the date of the presidential elections. But any council recommendation to hold early elections would go to both houses of parliament for approval. If Otan dominates tomorrow's Senate selection process, approving early elections will likely be a formality.
Otan was formed after the last presidential elections in 1999 with the express purpose of reelecting Nazarbaev.
(Merhat Sharipzhan of the Kazakh Service contributed to this report.)