Japan's prime minister, under pressure to resign within weeks, has declined Washington's invitation for a visit to hold talks with President Barack Obama next month.
Chief Cabinet Secretary Yukio Edano announced the decision Friday, citing "Japan's political situation," suggesting uncertainty over Prime Minister Naoto Kan's leadership.
Kan has faced a strong challenge from party rivals who have demanded his resignation. Kan has said he will step down when a pair of key bills are approved in parliament, which is likely next week. That would set the stage for a leadership election within Kan's ruling party, expected by the end of the month.
"It is extremely regrettable that we have to rearrange a visit at the invitation of President Obama," Edano said. "We will reschedule a visit at an appropriate time as we continue our effort to achieve unshakable Japan-U.S. relations."
Obama invited Kan to the U.S. for talks in early September when the two leaders met in France during May's Group of Eight summit. The March disaster had forced Kan to postpone his earlier plan to visit the U.S. in the first half of this year.
Kan and his Cabinet have faced criticism over their handling of the March 11 disasters due to a perceived lack of leadership as the disaster survivors grew frustrated by slow-paced relief and reconstruction efforts.
The earthquake and tsunami wiped out large parts of Japan's northeast coastline and left just over 20,000 people died or disappeared. Another 100,000 people were forced to evacuate their homes due to radiation threats from the tsunami-damaged Fukushima Dai-ichi nuclear power plant, whose reactors have melted down in the first few days of the crisis.
As Kan's days are numbered, Japanese media have shifted their focus to candidates to be his successor. Among several reported frontrunners are Finance Minister Yoshihiko Noda and trade and industry minister Banri Kaieda.
Kaieda, who has several policy disputes with Kan over the nuclear crisis management over the past weeks, has vowed to resign from his current post.
Suggesting a possibility of having a new prime minister within weeks, Edano said he believed "a prime minister at that point" would attend the United Nation's General Assembly in September.
Edano said Foreign Minister Takeaki Matsumoto recently informed U.S. Ambassador John Roos of Kan's cancellation of his U.S. trip and obtained Washington's understanding.
Kan's successor would be the sixth prime minister in five years.