President Carter's new taxing and spending plans came under attack yesterday from both liberals and conservatives.

Liberal Democrats and a coalition of normally Democratic unions and religious groups charged that Carter's fiscal 1979 budget is too austere and that it neglects "human" needs such as education and job creation.

The House Republican leadership, on the other hand, said the President's budget seriously, and perhaps intentionally, underestimates spending in fiscal 1979, which begins Oct. 1. House Minority Leader John J. Rhodes (R-Ariz) said that the projected, $61 billion deficit could swell to $99 billion or more.

Rhodes called the first Carter administratiin budget a "fiscal time bomb sett to explode with destructive inflationary force in the years ahead." He said that Republicans would offer an alternative budget within the next few weeks.

The attacks on Carter's economic policies came on a day when the Commerce Department announced that its index of leading economic indicators rose a strong 0.7 per cent in December, suggesting that the economy will continute to grow and create jobs for at least the first six months of 1978.

That is in line with administration projection and most other economic forecasts.

Carter [WORD ILLEGIBLE] Congress last week a $500.2 billion 1979 budget that he described as "lean and tight." It calls for a sizable increase in defense spending, but contains few other initiatives and asks for relatively small increases (that barely cover inflation) in areas besides defense.

The administration has also proposed a $25 billion tax cut.

The House Ways and Means Committee continued hearings on that proposed tax package with administration witnesses facing a generally cool re- ception on the revenue-raising "reform" portions of the plan.

Yesterday Charles L. Schultze, chairman of the Council of Economic Advisers, and James T. McIntyre, director of the Office of Management and Budget, reiterated Carter's hopes that the panel will keep the tax package intact.

The Presiden'ts budget plans got as critical a reception as his tax revisions.

Rep. Parren J. Mitchell (D-Md.), chairman of the House Budget Committee's Human Resources Task Force, charged that the president not only neglected human needs in his 1979 budget but also reneged on a campaign pledge to trim defense spending by $5 billion to $7 billion a year.

Mitchell spoke on behalf of a broad coalition of labor, minority, religious and other organizations that have pledted to try to refashion the president's budget in Congress. Mitchell said he would spearhead an effort to transfer monies from the defense budget to other areas such as job training, youth programs and education.

Joyce Hamlin, co-chairman of the coalition and an official of the United Methodist Church, said the Carter Budget shows his administration's values are "military values, not human values.

Carter's priorities also came under attack at a hearing of the Joint Economic Committee of Congress.

Sen. George McGovern (D-S.D.), who just replaced the late Sen. Hubert H. Humphrey on the committee, called the 1979 budget a "weak response" to the needs of the nation's cities, farmers and jobless.

He told Schultze (who appeared at two congressional hearings yesterday) that the administration should abandon its proposed $25 billion tax cut and instead use the funds to make a "public investment" of $12 billion in the cities, $7 billion in agriculture and $6 billion to upgrade the nation's railroads.

A report by the committee staff released yesterday said that tax cuts must be supplemented by other measures to assure an adequate growth rate in 1979. It urged an additional $7.5 billion in spending programs, and called for an expansionary monetary policy designed to boost the economy's growth rate and cut the unemployment rate more than the administration's budget contemplates.

While the President was facing criticism from his liberal Democratic constituents who feel abandoned by what they see as his tight spending policies, he was severely criticized by Republicans who charged just the opposite.

Rhodes said that while Carter's spending plans are "wrapped in the tissue of conservative rhetoric, this allegedly 'restrained' budget will swell our deficit far above its present level, like rice in boiling water."

Rhodes said the president has underestimated spending on crop support programs and Small Business Administration disaster loans to farmers by about $6 billion.

He said Carter assumes spending cuts of $3 billion that he knows Congress will not make, including funds for veterans' benefits, dams and small business.

Rep. Barber B. Conable Jr. (R-N.Y.) said Congress will not enact the $9 billion of revenue-raising measures that are the "reform" portion of his tax package and are assumed in the proposed 1979 budget.