On a day of bitter internal conflicts, the Democratic National Committee yesterday sent two seemingly conflicting messages to politically attentive voters: It reaffirmed an alliance with organized labor that many moderate Democrats consider too close for comfort, then turned around and repudiated its black caucus' claim to speak for the black voters, who have been the most loyal supporters of the Democratic ticket.

By electing Paul G. Kirk Jr., who was strongly supported by the AFL-CIO and its allied unions, as new party chairman, but dropping Mayor Richard G. Hatcher of Gary, Ind., the black caucus endorsee, as a vice chairman, the party seemed to be going in two directions at once.

The actions may have fit a larger pattern, inasmuch as there were clear parallels on the two key votes, but they added to the divisions confronting the Democratic Party and its newly installed leadership.

Kirk, a Boston-Washington lawyer who has spent most of his political career on the Senate and campaign staffs of Sen. Edward M. Kennedy (D-Mass.), was opposed by a coalition of southern and western Democrats backing former North Carolina governor Terry Sanford. They argued, as Rep. Steny H. Hoyer (D-Md.) put it, that it would damage the party "at least in the short term, for the message to go out that labor and Kennedy put it together and elected their guy."

Those moderate-conservative elements were thoroughly routed by the alliance of labor, liberals and organization Democrats backing Kirk. Not only was Sanford defeated, but the other three western and southern candidates seeking top posts -- Nancy Pelosi and Duane Garrett of California and William Crotty of Florida -- were knocked out of the running.

But just as the southern-western moderates were about to lick their wounds and leave town, feeling as frustrated as they did after the San Francisco convention last July, there was an unexpected turn of events that put a different light on Kirk's ascendancy.

The new chairman announced that he would offer no slate of his own for the vice chairmen's posts, thus rejecting strong pressure from the DNC black caucus that he rule out any challenge to Hatcher, their choice for a vice chairmanship traditionally reserved for a black. That left the way clear for Illinois comptroller Roland Burris, beaten by Hatcher in the black caucus endorsement fight, to pursue his candidacy in the full committee.

Burris beat Hatcher by 50 votes, with his strongest support coming from the same organization states -- Illinois, Massachusetts and Michigan, for example -- and the labor-dominated at-large delegation, which provided Kirk with his biggest blocks of votes.

Hatcher and other black caucus leaders immediately denounced labor and the new chairman for the tactic. It was clear that if Kirk did not engineer the coup, he certainly did nothing to prevent it -- as retiring chairman Charles T. Manatt did when Hatcher became vice chairman four years ago.

Hatcher had created his own problems. When he took the lead in the Rev. Jesse L. Jackson's presidential campaign in 1984 and condemned the party delegate-selection rules he had previously supported as vice chairman, many of his colleagues on the national committee were bitter.

Burris, who described himself yesterday as a man "whose style is to cooperate and work within the system," pledged that he would endorse no one for president during the primaries and caucuses in 1988.

For those moderates who believed that the national party had let itself be led around by the nose by its "organized minority caucuses," the defeat of Hatcher was an unexpected signal of change. But Kirk's and Burris' victories seemed to signal that another caucus -- organized labor -- was as influential as ever, at least for now. And the South and West are still as little represented in party leadership as they were on the last national ticket.From angry blacks to estranged southern conservatives and West Coast fund-raisers, Kirk has a lot of fence-mending to do.