A group of more than 30 conservative Democrats who will represent the balance of power in the House next year have organized to bargain with the leadership for a larger say in party affairs.

They call themselves the Democratic Conservative Forum and they met with Speaker Thomas P. (Tip) O'Neill Jr. for an hour Tuesday to lay out their requests for more important committee assignments and to urge that House Democrats take more "moderate" positions as the best way to hold control of the House after 1982.

It was the first time that O'Neill, an old-time liberal, had met with the most conservative members of his party in the House. This in itself showed he has accepted the fact that as a result of the Nov. 4 election liberals will no longer control the House and that he is at least willing to sit down and talk with the right wing of his party.

O'Neill called the meeting "amiable." He said the conservatives "feel they have been ignored in important committee assignments. It may well be that they have. They organized on the theory that the squeaky wheel gets the grease."

The group gave O'Neill a list of members they would like to see named to committee vacancies or party whip. He made no promises except that he would meet with them on a regular basis. O'Neill said he understood they would not be part of an effort by some Republicans to form a coalition to oust him as Speaker and elect a conservative.

The member who took the lead to form the Conservative Forum even before the election had cut the Democratic House majority by 33 seats was first-term Rep. Charles W. Stenholm of Texas. He told a reporter that conservative Democrats feel they have been left out from under the party umbrella. He said they asked for a meeting with the speaker to say they want to work within the party to seek middle-ground legislative positions fought out within the caucus of all House Democrats.

Aides said O'Neill had a feeling of being pushed when Stenholm spoke of being prepared to "meet liberals on the battlefield." Stenholm said he meant by that arguing in caucus to reach consensus, not trying to lop off each other's heads.

Stenholm said no threats or demands were made on the speaker. The group did specifically request an extra seat for them on the House Democratic Steering and Policy Committee where party policy and committee assignments originate. He noted that blacks, women and first-term members have their own representatives on the policy committee and that each of those groups numbers less than the Conservative Forum.

Stenholm called the meeting a "first step . . . the best thing he said he would meet with us on a regular basis."