TOKYO — Prime Minister Shinzo Abe of Japan resigned on Friday because of ill health, just four days after he exceeded the record for the longest consecutive run as leader in Japanese history.
Mr. Abe, 65, had been prime minister for nearly eight years, a significant feat in a country accustomed to high turnover in the top job. During his tenure, he oversaw Japan’s recovery from a devastating earthquake, tsunami and nuclear disaster, restored a semblance of economic health and curried favor with an unpredictable American president, Donald J. Trump.
Yet despite his long hold on power — his second stint as prime minister, having held the post in 2006-7 — Mr. Abe failed to reach some of his signature goals. He was unable to revise the pacifist Constitution installed by postwar American occupiers, or to secure the return of contested islands claimed by both Japan and Russia so that the two countries could sign a peace treaty to officially end World War II.
Mr. Abe said during a news conference Friday evening that he had suffered a relapse of the bowel disease that led him to resign during his first stint in office. He said he wanted to make way for a new leader who could focus fully on tackling the challenges facing Japan, chiefly the coronavirus pandemic.
His conservative governing party, the Liberal Democratic Party, is expected to appoint an interim leader who will serve until the party can hold a leadership election, according to NHK, the public broadcaster. Mr. Abe’s term was set to expire in September 2021.
The leading candidates to replace Mr. Abe include Taro Aso, the long-serving deputy prime minister and a former prime minister; Yoshihide Suga, the chief cabinet secretary to Mr. Abe; Shigeru Ishiba, a former defense minister who once ran against Mr. Abe for party leader; Fumio Kishida, a former foreign minister; and Taro Kono, the current foreign minister.
Mr. Abe said that party executives were finalizing plans for selecting a new leader.
Japanese stocks fell as much as 2 percent on Friday afternoon following the report of Mr. Abe’s planned resignation.
The Japanese news media had been speculating about Mr. Abe’s health for weeks, particularly after he significantly dialed back public appearances as a new wave of coronavirus infections erupted in clusters throughout the country. When Mr. Abe visited a hospital twice in the span of a week, the rumor mill went into overdrive.
Earlier on Friday, Yoshihide Suga, Mr. Abe’s chief cabinet secretary, had reassured reporters that Mr. Abe intended to stay in office. “The prime minister himself has said he would like to work hard again from now on, and I’m seeing him every day,” Mr. Suga said in a news briefing, saying that the prime minister’s health “remains unchanged.”
Mr. Abe, the grandson of a prime minister accused of war crimes and the son of a former foreign minister, began his first, yearlong stint as prime minister in 2006. As he resigned in 2007 under a cloud of scandal, he cited the debilitating effects of ulcerative colitis, a bowel disease.
In June, he said on Friday, he was told that doctors had found signs of a relapse of the disease. He said that in the months since he had lost much of his strength, and that he would now step aside so he could receive treatment with a new drug that he called promising.
He said he would remain a member of the lower house of Japan’s Parliament and continue to help his party pursue its goals.
During his second period in office, which began in late 2012, Mr. Abe survived influence-peddling scandals and rode out numerous elections. In 2015, he pushed through contentious security legislation that permitted Japanese troops to engage in overseas combat missions alongside allied forces, as part of “collective self-defense.”
His political power peaked in 2017, when his party won a landslide victory that gave it, along with its coalition partners, two-thirds of the seats in Parliament. That was the supermajority required to push through a constitutional revision, but Mr. Abe never brought that dream to fruition, with public opposition to such a change remaining high.
Mr. Abe, who was in office when Tokyo won its bid to host the 2020 Summer Olympics, will step down before he could preside over the Games, which were postponed to 2021 because of the pandemic.
By the time he signaled his intention to resign, Mr. Abe was a hugely unpopular leader whose disapproval ratings had risen to their highest level since he began his second term.
The public was dissatisfied with his administration’s handling of the coronavirus, particularly its effects on the economy, which erased what achievements he could claim under his economic platform, known as “Abenomics.”
Under that program, Mr. Abe had administered a three-pronged plan of monetary easing, fiscal stimulation and corporate reform. Most of its promises of corporate reform — including efforts to empower women, reduce the influence of nepotism and change entrenched work culture — remained unfulfilled.