Japan's Prime Minister Taro Aso has dissolved parliament and called a national election on 30 August, after gaining official cabinet backing, BBC reported.
Mr Aso called the elections early after his Liberal Democratic Party (LDP) lost control of Tokyo's municipal assembly.
Opinion polls suggest that the LDP could lose heavily to the opposition Democratic Party in the upcoming vote.
A win for the Democratic Party would end five decades of almost uninterrupted rule by the LDP.
On Tuesday morning, his cabinet gave its formal backing to Mr Aso's plan.
Japan is in a deep recession and correspondents say that at times the prime minister has appeared indecisive.
Last week, Mr Aso survived a no-confidence motion put forward by the opposition in the lower house. But the upper house, which is dominated by the opposition, passed a similar motion.
Mr Aso's position had been further weakened after the LDP lost control of Tokyo city council in elections on 12 July.
LDP rebels had sought to remove him before he could dissolve parliament, believing he is leading them to an historic defeat.
Polls published by the Asahi and Mainichi newspapers on Monday suggested that support for Mr Aso had continued to decline since previous surveys last month.
They show him trailing Democratic Party leader Yukio Hatoyama.
Correspondents say the Democratic Party favours more independence from the US, a greater Japanese contribution to peacekeeping missions, and a smaller role for government.
Mr Aso is the fourth prime minister since the party won the last election to the more powerful lower house of parliament in 2005.