"The employment situation has worsened as he repeated pork-barrel handouts in obvious vote-buying, none of which has helped to improve the lives of the people," he said.

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Japan PM under pressure

"The cabinet has been spending large amounts of money for the economy but we can only think that it was aimed at winning support for the election."

While the motion had no chance of passing, analysts say the Democrats were hoping that by forcing LDP lawmakers to back Aso, it would make it harder for critics in his own party to maintain efforts to dump him ahead of the election.

Alarmed by Aso's plunging support levels, several senior LDP figures have openly called for him to quit ahead of the election and bring forward a vote for the party leadership set for September.

A similar censure motion against Aso was easily passed by the less powerful upper house of parliament, where the Democrats have a majority.

However the vote in the upper house carries no legal weight without the backing of the lower house.

Test of strength

The current round of manoeuvring follows a municipal election in Tokyo over the weekend in which Aso's LDP was routed by the Democrats and lost their majority.

The vote does not directly affect the national government but was widely viewed as a test of strength of the two parties.

After the results were released on Monday, Aso announced he would dissolve parliament next week and call general elections for August 30.

Apart from a brief period in 1993, the LDP has governed Japan for the past 50 years.

But recently the party has been struggling to maintain its grip on power and recent newspaper opinion polls have suggested the opposition party is well-placed to make gains.