By Jeremy Pelofsky

WHITE SULPHUR SPRINGS, W., Virginia (Reuters) - U.S. President George W. Bush said on Friday he was confident in the long-term strength of the U.S. economy, but urged lawmakers to act swiftly on a stimulus plan he and others hope will help stave off a possible recession.

"I strongly believe it would be a mistake to delay or derail this bill," Bush told his fellow Republicans from the House of Representatives who are attending an annual retreat.

He said the economy's underpinnings were solid but added it needed a temporary boost that would be provided by the election-year package of tax breaks for businesses and government rebates to individuals and families.

Bush and leaders in the Democratic-led House on Thursday unveiled a package of about $150 billion in tax rebates and business investment tax breaks aimed at stimulating consumer and business spending and giving a boost to the economy that has been suffering from high oil prices, a housing market slump and a subprime mortgage crisis.

"It's a sound package. It makes a lot of sense. It's needed and you need to pass it as quickly as possible to get money in the hands of the people who are going to help this economy stay strong," Bush said.

The package must first pass the House before it heads to the Senate, where it will be subject to changes. The House is expected to act quickly on the deal negotiated by House Speaker Nancy Pelosi, a California Democrat; House Minority Leader John Boehner, an Ohio Republican, and Treasury Secretary Henry Paulson.

SENATE MAY DO SOME TINKERING

Boehner told reporters that the House would act quickly on the plan, but expressed concern that momentum could slow in the Senate.