Abe has spent a total of 2,887 days as leader during two periods in office, beating the previous record set by Taro Katsura more than a century ago.
At 52, Abe was Japan’s youngest prime minister when he first became leader in 2006, but left office a year later amid scandal and questions over his health.
He became prime minister for a second time at the end of 2012 promising to resurrect the economy after two decades of stagnation, strengthen Japan’s military and revise the US-authored constitution.
Abe and other conservatives see the constitution, which forbids Japan from using or threatening force to settle international disputes, as an outdated constraint on Japan’s ability to defend itself against a nuclear-armed North Korea and a more assertive China.
Despite failing to enact structural reforms, including increasing the number of women in senior public and private roles, and weathering several cronyism scandals, analysts say Abe has benefitted from a weak and divided opposition and a desire for stability among voters.
“Abe’s tenure has made Japan an island of political stability even as other advanced industrial democracies have suffered from weak, unpopular, or short-lived governments over the course of the decade,” said Tobias Harris, a Japan expert and vice-president of Teneo Intelligence, a Washington-based consultancy.
Recent opinion polls suggest that Abe’s Liberal Democratic party’s position is unassailable and that he is likely to continue as leader until at least September 2021.
A poll by the public broadcaster NHK this month showed support for the LDP at 36.8%, putting it well ahead of the largest opposition Constitutional Democratic party on 6.3%.
Abe claims to have formed a close relationship with Donald Trump but has also failed to make much progress on several foreign policy fronts.
Kim Jong-un has rebuffed Abe’s offers to meet, without preconditions, to discuss the issue of Japanese citizens abducted by North Korea during the cold war, while Abe appears no closer to settling a dispute with Russia over ownership of a group of islands than when he took office.
In recent months, relations between Japan and South Korea have sunk to their lowest level in recent memory, as the two countries remain at odds over their bitter wartime legacy.
Amid concern over an economic slowdown and a fresh political scandal at home, Abe showed little appetite for celebration on Wednesday as he fielded questions over a fresh political scandal.
He faces accusations he invited supporters to a government-funded cherry blossom party in Tokyo and that his office may have broken campaign laws by paying part of the cost for them to attend a reception the night before.
Abe has denied any wrongdoing, but a poll by the Asahi newspaper showed 68% of respondents were unconvinced by his explanations.
Assuming he survives the latest scandal, Abe is expected to turn his attention to revising the constitution to give legal recognition to Japan’s self-defence forces.
But the move, which would require a two-thirds “super” majority in both houses of parliament and a simple majority in a referendum, has divided voters, leading some to question his ability to implement a reform – a failure that could come to define his political legacy.
“Prime Minister Abe will definitely go down in history,” said Shinichi Nishikawa, professor of political science at Meiji University in Tokyo. “But the chances of achieving his ambitious goals are very, very slim.”
More about: Japan