At age 6, the Democratic Leadership Council -- the self-styled "mainstream voice of the Democratic Party" -- is ready to slug it out for control of the party's agenda and future.

Strengthened by a grass-roots organizing drive that in six months has launched chapters in almost half the states, the DLC on Sunday will open its first national convention in Cleveland. The mission of the three-day meeting is to dispel what the DLC says in draft resolutions is a widespread belief that Democrats support "government programs that don't work," put "special interests before the interests of ordinary people" and exhibit "a reluctance to assert American values at home and abroad."

Convention organizers, determined to step boldly into the party's post-1988 policy vacuum, say the expected 1,000 delegates will bury the notion that Democrats are still wedded to "New Deal policies" of the past. The advance controversy the session has stirred indicates that its critics at least are taking the DLC seriously.

In recent days, two-time presidential candidate Jesse L. Jackson and Democratic National Chairman Ronald H. Brown have reacted angrily to suggestions from DLC leaders that the group is ready to take over the party. Less publicly, some of DLC's own founders and officials have questioned where its chairman, Arkansas Gov. Bill Clinton, and its president, hard-driving political operative Alvin From, are pointing the organization.

Controversy surrounds the meeting. Organized labor, which has been suspicious from the outset of DLC and its long list of business lobbyist sponsors, has discouraged union officials from attending. A column saying the gathering would pass a litmus-test resolution condemning Democrats who opposed the Persian Gulf War "really got the phones ringing," said Rep. Barbara B. Kennelly (Conn.), a DLC vice chairman and opponent of the war.

Then came a From interview pointedly publicizing the decision not to give Jackson a speaking invitation. And to top it off, Clinton was quoted as saying the DLC would soon be strong enough to supplant the Democratic National Committee as the focus of party activity.

Tempers were frayed; apologies, corrections and denials were issued; and suddenly a lot of folks were asking, "Who are these people?"

They are, for the most part, elected Democratic officials who believe that their party's presidential nominating process has pulled candidates too far left to win the White House and that the national committee and the party as a whole have become too responsive to organized constituency groups on the liberal end of the spectrum.

Their goal, as stated by Clinton, is to "define a new middle ground of Democratic thinking on which someone can run for president and be elected." Officially, DLC has no choice for the job, but potential 1992 candidates addressing the Cleveland meeting include Sen. Albert Gore Jr. (Tenn), Virginia Gov. L. Douglas Wilder and Clinton.

The DLC started in 1985 as a "safe house" for worried conservative southern Democrats, who saw that after nominating Walter Mondale for the disastrous 1984 presidential campaign, the national party was about to install Paul Kirk, a former aide to Sen. Edward M. Kennedy (Mass.), as its chairman. Although northern urban representatives like Kennelly and Rep. William H. Gray III of Pennsylvania have been added to the leadership, DLC's chairmen all have come from southern or border states.

The divisions within the DLC, according to Rep. Dave McCurdy (Okla.) and others, pit those (including McCurdy) who "are willing to draw distinctions with other Democrats" against those who prefer the "big tent" approach. In the first camp are Sens. Sam Nunn (Ga.) and Charles S. Robb (Va.), who launched the DLC and hired From as its president, and Sen. John B. Breaux (La.).

In advance of last year's DLC conference in New Orleans, the three senators made the decision to recruit Clinton as the first non-Washington chairman and to expand the organization's base beyond the Beltway by organizing state chapters. It is this nascent national structure -- and its potential in presidential politics -- that has given the Cleveland meeting (the first the DLC has called a "convention," not a conference) its added muscle.

Clearly unsettled by the organization's growing militancy are its first chairman, House Majority Leader Richard A. Gephardt (Mo.) and his House allies, Kennelly and Gray. On Wednesday, Gray told the Arkansas Democrat that From "should look for another job" after getting into a battle with Jackson.

Gephardt said in an interview that "some in DLC think it should give the party a more mainstream, moderate, middle-of-the-road cast. But I always thought we should be inclusive of all views, conservative or liberal -- really a policy forum."

Clinton, who began in politics working for George McGovern and nominated Michael S. Dukakis at the 1988 convention, tries to bridge the gap. The draft resolutions reflect the pulling and hauling within the organization.

Instead of the rumored "litmus-test" resolution on the gulf war, the draft resolution entirely skirts the sanctions-versus-force issue that split the DLC leadership. It praises the conduct of the war, but faults administration policy before the hostilities and since.

"We disagree with those who view the use of force as inherently wrong," the draft resolution says. "The U.S. cannot police the globe, but neither can it retire from an interdependent world and be a passive exemplar of democracy."

The domestic planks draw more battle lines. They endorse cuts in Social Security taxes for middle-income workers, just rejected by the Democratic-controlled Senate, and a seven-day waiting period for handgun purchasers, opposed by the Democratic leaders of the House and Senate. In a direct challenge to organized labor, the draft resolution calls for a free-trade agreement with Mexico.

Renewing a dispute with Jackson that marked its 1989 meeting in New Orleans, the DLC draft resolution endorses affirmative action but asserts, "Government cannot mandate equal outcomes; therefore we oppose quotas and public policies that enshrine racial, gender or ethnic preference."

Jackson, who said in an interview that the DLC is seeking "to suburbanize the Democratic Party," will reportedly go to Cleveland Monday to support striking bus workers and draw coverage away from the DLC convention.

Brown said he had agreed to address the convention after receiving an assurance from Clinton that Clinton was misquoted in a newspaper story which had the governor saying, "I'd like us {the DLC} to be what people think of when they think of the Democratic National Committee."

Brown said he has "a great relationship with their elected leaders," but in an apparent reference to From and Will Marshall, head of the Progressive Policy Institute, part of the DLC, he added, "There are some people associated with DLC who want to have a fight with the party."