Japanese Prime Minister Yoshiro Mori, one of Japan's most unpopular leaders in decades, told his Cabinet on Friday that he will resign, but did not set a date, the government's top spokesman said.

Mori had long been expected to resign. The ruling Liberal Democratic Party is planning to hold a leadership election later this month that would choose a successor.

But Friday's announcement was the first time Mori had directly said publicly that he would step down.

"I made up my mind to resign because I think it is necessary to tackle mounting issues both at home and abroad under a new administration," Chief Cabinet Secretary Yasuo Fukuda quoted Mori as telling the Cabinet.

The changing of the guard comes as Japan is struggling to overcome a decade-long economic slowdown. Stocks have slumped, unemployment is near a record high and officials say a long-awaited recovery has stalled.

The LDP began preparations this week to hold elections on April 24 for a new party president. The LDP president is almost guaranteed to become prime minister because of the party's domination of Parliament.

The date still needs to be approved by other party officials and a final decision was scheduled for Tuesday.

Mori hinted strongly last month that he would step down soon by calling for the LDP's leadership election to be pushed up from September.

Former Prime Minister Ryutaro Hashimoto appears to have become the front-runner. Hashimoto heads the party's largest faction and reportedly has the support of two other factions.

Junichiro Koizumi, a former health minister who had been named as a possible successor to Mori, appeared to be losing support because he has provoked distrust within the party with his calls to privatize the postal service.

Another possible candidate, Hiromu Nonaka, who is a member of Hashimoto's faction, has said he does not intend to run.

Mori's tenure, which began last April after Prime Minister Keizo Obuchi suffered a fatal stroke, has been marred by scandals and gaffes. He has repeatedly come under fire for his remarks evoking the nationalism of Japan's wartime leaders.

His public support ratings have plunged below 10 percent, making him the second-most unpopular prime minister Japan has had since World War II.

The LDP has been under intense pressure to replace Mori ahead of elections this July for the upper house of Parliament.