throw one's hat in (or into) the ring

驚きましたね。これって前々から決まっていたのでしょうか。12人の理事が出馬を表明する，throw their hats in （the ring）は「土俵」ringにかけた言葉遊びです。でも実際にはどろどろした感じがするのはわたしだけでしょうか。（ゼミ生 Temple Gate）
Sumo: Kitanoumi elected to 2nd stint as JSA chief

TOKYO (Kyodo) -- Former Japan Sumo Association Chairman Kitanoumi, who resigned in disgrace in 2008 in the wake of a scandal, on Monday became the first in the history of the sport to return to the governing body's top spot.

The 58-year-old Kitanoumi replaces Hanaregoma, who stepped down as part of the JSA Board reshuffling, since he will reach the retirement age of 65 in February 2013.

Kitanoumi became the 12th JSA chairman, elected in a vote among 10 newly elected directors.

"Most importantly, we have to arrange a crisis management system, making strong efforts to avoid a recurrence of scandals," said Kitanoumi. "The sumo association must protect the traditional Japanese sport. I am prepared to devote my life to work for the prosperity of sumo."

Twelve people -- the most since the current candidate system was established in 1968 -- [[threw their hats in for the JSA board of directors' election,]] which is held once every two years. Kokonoe (former yokozuna Chiyonofuji) was among the 10 elected to the executive board.

http://mdn.mainichi.jp/mdnnews/sports/news/20120131p2g00m0sp127000c.html