the Changing of the Guard

change of the guardは文字通り、「守衛の交代」という意味もあります。「（英国バッキンガム宮殿の）衛兵交替」を”the Changing of the Guard”という表現をしますが,この見出しはそれをもじったものです。
『ジーニアス英和辞典　第４版』(大修館)には「政権(指導者)交替」という意味が記載されていました。似たような意味のguard mountingも押さえておきます。(Minnesota)

Changing of guard in Japan as PM concedes vote

CNN) -- Japan's prime minister conceded defeat in parliamentary elections Sunday, signaling the return to power of the Liberal Democratic Party and ending the brief rule of the disappointing upstart Democratic Party of Japan.

Prime Minister Yoshihiko Noda pledged to step down as party president after exit polls showed a smashing loss in lower house voting. The party, once seen as a breath of fresh air in Japanese politics, came to be regarded as increasingly ineffective.

"We got a regrettable result," Noda said. "The result is everything in the politics. The biggest responsibility lies on me. I will quit as the partly leader of DPJ."

http://edition.cnn.com/2012/12/16/world/asia/japan-election/index.html?hpt=ias_c1