Naoto Kan, the embattled Japanese prime minister, is likely to step down by early next week, a cabinet minister said on Tuesday, a long-expected resignation that will nevertheless bring uncertainty to a country still reeling in the aftermath of its natural and nuclear disasters. Japans economics minister, Kaoru Yosano, quoted Mr. Kan as saying that he believed his cabinet would resign and a new prime minister would be decided next Tuesday. Ministers were told to do their best with their remaining affairs and prepare for a handoff, Mr. Yosano quoted Mr. Kan as saying at an informal cabinet meeting Tuesday. Even before the March 11 earthquake, tsunami and nuclear accident, Mr. Kan, 66, had already been unpopular, criticized for his perceived haplessness in both foreign and economic policy. A series of blunders in response to the disasters has won Mr. Kan more disapproval, including a delay in admitting that the accident at the Fukushima Nuclear Power Plant was far worse than previously announced.