Ways and Means Democrats, attempting to retain a patina of party tradition in their tax bill, yesterday lined up behind individual cuts geared to persons making $50,000 a year or less.

The Democratic bill, which is expected to be approved by the committee in a partisan vote today, would cut individual taxes in 1982 by $40.2 billion. Of this amount, 79.1 percent would go to those making less than $50,000, according to the Joint Committee on Taxation. By contrast, the GOP measure, as reported by the Senate Finance Committee, would give this group 64.9 percent of a $36.4 billion cut in 1982.

"In all fairness and equity, when we get to the income tax, we ought to look at the middle class to see that they get some benefits," said Rep. Ed Jenkins, a conservative Georgia Democrat. Jenkins pointed out that many of the other provisions in the Democratic bill are geared to the upper middle class and rich, including liberalized estate taxes, deductions for income earned overseas and reduced tax liability for retirement accounts.

In an outline of the debate expected on the House floor later this month, Republicans on the panel sharply attacked the Democratic bill on two key grounds: that it fails to reduce rates over three years and that by increasing benefits for the poor and middle class, it will fail to encourage adequate new savings and investments by upper-income persons.

Rep. W. Henson Moore (R-La.) contended that the Democratic bill will give an excessive share of the tax cut to the poor and lower middle class, who will "spend every dollar" while failing to give enough to persons in the upper brackets "where you are going to get most of your savings and investment." Moore and fellow Republicans are pressing for the Reagan administration's proposal to cut income tax rates across the board by 25 percent over three years.

As the committee continued to mark up the legislation, Republican and Democratic strategists prepared to mount separate intense lobbying campaigns aimed at pressuring individual members through their campaign contributors and newspaper, radio and television outlets in their districts.

A "boiler room" set up by Democrats in the Capitol has telephone banks to call newspaper editors in the districts of key southern Democrats and Frost Belt Republicans.

In addition, Charles T. Manatt, chairman of the Democratic National committee, has begun to contact members of the Democratic National Finance Council -- persons who have contributed $5,000 or more to the party -- in an effort to persuade them to contact individual members of Congress, according to DNC officials.

Republicans are planning to produce a series of television advertisements and have discussed possible commercials with the media firm of Bailey, Deardourff and Associates.

Dick Leggitt, administrative assistant to Rep. Stanford E. Parris (R-Va.), who helped engineer a GOP lobbying effort in the May budget fight, said he is hoping to be able to tap into a $400,000 fund held by the Republican National Committee to finance the promotion campaign for the Reagan tax cut.

The core of the argument used by Ways and Means committee Democrats in support of their targeted income tax reductions is that without the "skewing," all the benefits for the poor and lower middle class will be severly weakened or eliminated by inflation and mandated increases in payroll deductions for Social Security.

Joint taxation committee figures showed, for example, that for persons earning from $10,000 to $15,000, the Republican Senate bill would result in increased tax liabilities of $684 in 1982 when inflation and Social Security are taken into account. Under the Democratic bill this group would see their taxes lowered by an average of $454.

Similar figures comparing the Senate cut for those with incomes between $20,000 and $30,000 to the Democratic bill show that the net tax reduction would be $1,565 under the GOP plan, compared to $4,113 in the Democratic plan. For those in the $30,000-to-$50,000 income range, the net Republican reduction would be $3,085 while the Democratic reduction would be $6,710. The two plans come out about even in the $50,000-to-$100,000 range. For those making $200,000 or more, the net Republican cut would be $3,305 and the Democratic reduction would be $1,369.