Prime Minister Shinzo Abe is pledging to move quickly toward changing the Constitution, according to an internal campaign pamphlet seen by Bloomberg News, ensuring the divisive proposal is a key part of his bid for a historic third consecutive term as ruling party leader.

Abe intends to have the Liberal Democratic Party submit the amendment in the next Diet session and push for a speedy vote, according to the pamphlet, which was distributed to party lawmakers ahead of the Sept. 20 leadership election. The Sankei newspaper reported on the document late Tuesday.

The 63-year-old prime minister is expected to cruise to victory in the party ballot, fighting off a long-shot challenge from former Defense Minister Shigeru Ishiba. A win would bolster his chances of becoming Japan's longest-serving prime minister and may enable him to stay in power until late 2021.