NEW YORK — Americans increasingly blame President Bush and congressional Republicans for the nation's economic problems, a national poll said Saturday.More than 60 percent polled said they feared they would not have enough savings for their retirement or to pay for medical and health costs, and a majority said they were reluctant to invest in a new car or home. The number of Americans fearing their household will lose a major wage earner increased by 10 percent from the beginning of the year to 42 percent. The Gallop Organization conducted the poll for Newsweek magazine's coming cover story, "The Bite of the Middle Class," due on newsstands today. President Bush's approval rating slipped 10 points to 55 percent compared with a recent poll conducted between Oct. 17 and 20. The new poll found that Bush and congressional Republicans were blamed for the country's economic woes by a total of 58 percent of Americans, up from 48 percent questioned for the newsweekly on Jan. 5. Only 25 percent in the current poll blamed the economic downturn on congressional Democrats. But asked if a Democratic president would handle economic conditions better, only 28 percent said yes, while an equal number was uncertain and 44 percent said no. Half of those polled said a cut in taxes on middle-income Americans would help the economy a lot; slightly fewer supported tax credits for families with young children; less than a third supported Bush's proposal for a cut in capital gains taxes. Newsweek also reported that the number of people satisfied with their current standard of living had reached a new low of 62 percent, compared with 82 percent in 1981.