Washington ? Most Americans are planning to use their stimulus rebate checks to pay down existing debt or add to their savings, not to fuel the kind of consumer spending that would bolster the economy, a Los Angeles Times/Bloomberg poll has found.

Only 18 percent of respondents to the national poll said they intended to spend the money they would receive later this year from the federal government as part of an effort to inject cash into the economy. By contrast, 34 percent said they intended to save it and 31 percent intended to use it to pay existing debts. The rest thought that they either were not eligible for a rebate, would spend some and save some, would do “something else” with it or weren’t sure what they would do.

The rebate checks are the centerpiece of a $168 billion stimulus package passed by Congress and signed into law by President Bush earlier this month as part of an effort to fend off a recession.

Jared Bernstein, an economist with the Democratic-leaning Economic Policy Institute, said lawmakers assumed that Americans would spend at least half of the money on new purchases. “I’m pretty sure that’s wrong,” he said.

Most single taxpayers who earn no more than $75,000 will receive either $600 or a full refund of their 2007 tax paid, whichever is less. Most married couples who file a joint return and have a combined income of no more than $150,000 will receive either $1,200 or, if less, a full refund of their 2007 tax paid. As income levels rise, the amount of the payment becomes lower, with the payments phased out completely for single taxpayers making more than $87,000 and couples with a combined income over $174,000. Eligible taxpayers also will receive $300 for each qualifying child age 16 or younger.

The poll suggested that even lower-income respondents – those consumers most likely to spend the rebate on food and fuel – instead were leaning toward using it to pay down existing debt. According to the poll, 37 percent of people in households making less than $40,000 a year intend to use the check to pay off debt, 30 percent intend to save it and 18 percent will spend it all on purchases.

The poll, conducted under the direction of Times Polling Director Susan Pinkus, has a margin of sampling error of plus or minus 3 percentage points.