WASHINGTON - PRESIDENT Barack Obama said on Saturday more time was needed for his US$787 billion (S$1.2 trillion) stimulus package to work, predicting the spending would have a bigger impact on the economy later this year.

In an advanced text of his weekly radio speech, Mr Obama said the stimulus plan approved by Congress and signed into law in mid-February 'was not designed to work in four months - it was designed to work over two years.'

Mr Obama's comments follow government data showing the unemployment rate soared to 9.5 per cent in June, the highest level since 1983 and above the 8 per cent peak predicted by the White House when it worked with Congress to pass the package.

Republicans say the stimulus plan is not working. Mr Obama now warns unemployment will likely top 10 per cent in the coming months.

'We must let (the stimulus plan) work the way it's supposed to, with the understanding that in any recession, unemployment tends to recover more slowly than other measures of economic activity,' he said.

He said the benefits of the plan would 'accelerate greatly throughout the summer and the fall.' The ongoing recession and further steep job losses are wearing away the patience of Americans and raising doubts about Mr Obama's handling of the economy.

The share of Americans who believe the stimulus package will restore the economy slipped to 52 per cent in late June, down from 59 per cent two months earlier, according to a Washington Post-ABC News poll.

Vice President Joe Biden said the administration had 'misread' how bad the economy was when it took office, but that the stimulus package would help the economy recovery and create jobs.

Senate Republican Leader Mich McConnell said on Friday the stimulus plan 'was a failure.'

Mr Obama said it takes time for the plan's money 'to get out the door' to pay for roads, bridges and other infrastructure projects that will create jobs 'because we are committed to spending it in a way that is effective and transparent.' -- REUTERS