The House and Senate Budget committees -- the ugly ducklings of Congress past -- have suddenly blossomed into this year's swans.

In the jockeying for committee assignments in the 96th Congress, unusually high numbers of members, both veterans and newcomers, have requested assignment to the Budget committees.

The upsurge of interest in the Budget committees, which have not prevously ranked high in members' preferences, reflects the consensus in both parties that the battle over federal spending will be the chief domestic policy issue in both houses of Congress this year. The committees set spending targets for all federal agencies.

Other pocketbook-related committees, such as Appropriations and the tax-writing panels, also have strong attraction for members this year, according to party leaders in both houses. Another much-requested assignment is the Commerce Committee, especially among newly elected members.

"Commerce covers a lot of federal regulations of industry," explained Gary Hymel, an aide to House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass). "Thaths a big issur for these freshmen."

On the other hand, some committees that were hot tickets in the not-too-distant past, such as Judiciary and International Relations, have much less appeal to members today. Hymel says the leadership will probably have to force some members to accept assignment to *judiciary to fill its seats for the 96th Congress.

But the real surprise this year is the push for Budget Committee slots. When the committees were created four years ago, House and Senate members shied away because of uncertainty about how much they could accomplish. A House rule limiting membership on budget to four years also discouraged members from joining.

Now, according to Rep. Richard Bolling (D-Mo), of the Democratic Steering and Policy Committee, which recommends committee assignments to the Democratic Caucus, "Budget is certainly the one that people who have been here awhile want to get on most."

Robert Boyd, minority staff director of the Senate Budget Committee, reports a similar phenomenon on his side of the Capitol. "All of a sudden, we're getting an awful lot of attention," he said.

House members expect a fight in the Democratic Caucus over assignments to the House committee, where at least six of 17 majority seats will be open.

The generally liberal Democratic leadership is concerned that an influx of fiscal conservatives could reverse the committee's tendency to support the liberal position in priority-setting decisions. The effort to keep a liberal nucleus on the unit was the key reason for the caucus vote permitting current members whose four-year terms on budget were expiring to serve two more years.

Bolling said he would like to put together a "leadership slate" of nominees for the six vacant Democratic seats. But he said such a slate could prompt a battle in the caucus. "The conservatives have made it clear they want some of those seats," he said.

One veteran House member who has been a forceful, if sometimes futile, fighter for the "liberal" position -- that is, for increased spending on social programs -- is giving up his committee seat, however. Rep. Parren Mitchell (D-Md.), chairman of the Congressional Black Cucus, said he Congressional Black Caucus, said he is doing so partly out of frustration at the growing antispending mood in the House and partly because he wants to get back to the Small Business Committee seat he left to join Budget.

Mitchell said he has pushed the leadership to fill his seat on the Budget Committee with another black member. It is not coear whether his request will be granted. If it is not, Rep. Louis Stokes (D-Ohio) of Cleveland, will be left as the committee's only urban black member.

If Democratic seats go to conservatives, that should strengten some-what trhe outnumbered Republicans, who have little success to date in efforts to impose a belt-tightening mood on the committee. None of the eight Republican seats is Xpected to change this year.

On the Senate committee, a shift trward the conservatism seems probable. Republicans should gain an additional committee seat, reflecting the party's increased representation in the Senate, to make the party split 10 to seven. Further, the two departing Democrats, James Abourezk of South Dakota, who retired, and Wendell Anderson of Minnesota, who was defeated, both took a generally liberal position on spending issues.

The Senate committee has displayed more harmony than its sharply partisan House counterpart, but there are signs that the discord will increase somewhat this year. Chairman Edmund S. Muskie (d-m/aine) has received colse cooperation from the committee's ranking Republican, Henry Bellmon (Okla.), but Bellmon may leave Budget this year to take a seat on the Energy committee.

Muskie took some slaps from Budget Committee Republicans recently when he suggested that a federal deficit higher than President Carter's target of $30 billion might be tolerable. Bellmon said the committee's Republicans think the deficit ought to be smaller -- in the range of $25 billion or less.