The Democratic Platform Committee opens hearings in Washington today with formal presentations from the Carter and Kennedy camps, but neither the president nor the senator from Massachusetts will be in the room.

The Carter campaign had evidently hoped to entice Kennedy to the Sheraton Washington Hotel this morning to make his case for planks in this year's party platform, perhaps as a way of assuaging Kennedy's desire for a "debate" on the issues with President Carter.That, at least, is the Kennedy camp's interpretation, and Kennedy won't bite. He'll send a senior aide to speak in his place.

Carter is doing the same, deputizing his principal domestic affairs adviser, Stuart Eizenstat, and his nation security adviser, Zgibniew Brzezinski, to recommend party positions on domestic and foreign issues.

The platform committee will also approve a 15-member drafting subcommittee that will probably do the key work preparing a platform document for a final series of meetings that will begin June 21.The drafting committee is to consist of nine Carter supporters, five Kennedy supporters and Sen. Daniel Patrick Moynihan (N.Y.), who, because he exasperated both candidates at various times during the last six months, has been selected as an "independent." Gov. Richard W. Riley of South Carolina will be chairman.

Paul Kirk, director of the Kennedy campaign, met yesterday with Richard Moe of the White House to discuss the membership of this drafting committee. Kirk asked that six Kennedy supporters be included, but Moe insisted on just five, according to a spokesman for the Kennedy campaign.

The Carter camp insists that it wants to be forthcoming and friendly with Kennedy, but "there has to be a recognition that we won the damn thing fairly and squarely," as one White House official put the nomination fight yesterday.

James Flug, the Kennedy spokesman, questioned whether the offer of five seats on the drafting subcommittee was really "the purported hand of friendship" that the White House has advertised.

Conversations with officials in both Democrats' campaign organizations yesterday revealed that feelings between them remain strained or worse.

The Carter group is determined to say only affable things about Kennedy, insisting that it is "his right" to carry on the quest that they say flatly is futile. But the same people add that Kennedy's persistence will inevitably damage the Democrats in November.

In the Kennedy camp the feelings seem stronger. Kennedy aides continue to complain that the president is afraid to meet their man head-on in a debate over the issues.

The Carter camp seems confident that it can dominate the drafting of a platform, but members of the platform committee were all appointed by state party chairman, so they are not necessarily beholden to the White House. Carter campaign officials said today's session of the platform committee should provide clues about the general mood of the group. About 100 members are expected today.

Today's session, open to the public, will be in Exhibit Hall C of the Sheraton Washington Hotel, the former Sheraton Park. The meeting begins at 11 a.m. Members of Congress will testify after the Kennedy and Carter aides.