Thirty-four Democratic governors, the most promising element on an otherwise bleak partisan landscape, assemble in Washington this week to show themselves off as the future of their party.

But as the Democratic governors gather here with their Republican counterparts for the National Governors' Association's winter conference, party strategists are divided on how well -- and how soon -- this collection of individual strengths can transform the party's national prospects.

"In the governors, we're going to find the new Democratic Party," said political consultant Raymond Strother. "Not exclusively, but there are a lot of governors who are beginning to make the transition and beginning to define the new Democratic Party."

"They're young, a different generation -- the cusp of the Yuppies," said pollster William Hamilton. "They are less ideological, but still progressive, and they hold to the Democratic principles by and large."

Throughout the South, in most of the Mountain states and across the upper tier of the industrial Midwest and Northeast, young Democratic governors have written success stories in a language spoken by voters of both parties.

While maintaining reputations as fiscal conservatives, many have raised taxes and reduced spending to avoid pending economic doom. Several preside over modest budget surpluses.

Some have launched comprehensive plans to bolster educational systems and sprout jobs for barren state economies while enduring sharp cutbacks in federal assistance for human services programs.

Democrats are generally optimistic, but Republican strategists said the Democrats might do well to temper their expectations.

"When both parties have been down or having problems internally, there has always been this notion that the governors are going to be their salvation . . . and, interestingly, that's never been very true," said Republican pollster Robert Teeter.

"They produced some good people in the party," Teeter said. But "the commonality of interest never seemed to be there ultimately. They were busy with their own problems of governing their own states and their own political problems in their states."

The Democrats' good fortunes in the state capitals began in 1972, the same year the party's national prestige plummeted with the presidential candidacy of then-Sen. George McGovern (S.D.). That year, they picked up 11 governorships to raise their total to 29. The number has generally grown since then.

Most of the more prominent Democratic governors are young by national political standards. Arkansas' Bill Clinton, 38, is the youngest; Mario M. Cuomo of New York, 52, and Michael S. Dukakis of Massachusetts, 51, are the veritable senior citizens.

Those in between include Charles S. Robb of Virginia, 45; Bruce Babbitt of Arizona, 46; Robert Graham of Florida, 48; Mark White of Texas, 46; Anthony S. Earl of Wisconsin, 48; Richard F. Celeste of Ohio, 47; and James Blanchard of Michigan, 42.

The nation's only two woman governors are Democrats, Martha Layne Collins of Kentucky and Madeleine M. Kunin, recently sworn in as governor of Vermont. Toney Anaya of New Mexico, the only Hispanic governor, also is a Democrat.

The Republicans also have several prominent governors of similar age considered to have national political potential. They include Richard L. Thornburgh of Pennsylvania, James R. Thompson of Illinois, George Deukmejian of California, John H. Sununu of New Hampshire and Thomas Kean of New Jersey.

But the Democrats are generally considered to be in a more pivotal position inside their party because of their larger numbers and because of the party's more desperate search for new ideas and policies.

"The thing that seems so important is that there are so many good stories to tell coming out of the gubernatorial mansions," said Democratic pollster Peter D. Hart.

"From Dukakis to Babbitt to Mario Cuomo to Mark White to Bill Clinton -- they all have major success stories. It gives you a sense of Democratic leadership and Democratic philosophy," Hart said.

Sen. George J. Mitchell (D-Maine), chairman of the Democratic Senatorial Campaign Committee, is hoping to persuade some of the governors to run for Senate next year, especially in states where Republicans seem most vulnerable.

Even though governors and senators run statewide, however, transferring popularity often can be difficult, as former governor William F. Winter of Mississippi found out last year.

Winter has just completed a term as governor, with widespread praise, and Sen. Thad Cochran, the Republican incumbent, in 1978 barely won a three-way race in which the state's dominant Democratic Party was divided. Still, Cochran drubbed Winter in last year's two-way race, winning 61 percent of the vote.

The problem, Winter said, was that no matter how hard he tried to run as a governor, the issues kept making him a national Democrat.

Another popular former Democratic governor, James B. Hunt, failed to unseat arch-conservative Sen. Jesse Helms (R-N.C.). Three other Democrats, Richard W. Riley of South Carolina, Richard D. Lamm of Colorado and Joseph E. Brennan of Maine, declined to run, as did Republicans Lamar Alexander in Tennessee and Pierre S. du Pont IV in Deleware. Only John D. (Jay) Rockefeller IV of West Virginia, a Democrat, succeeded in making the transition from the statehouse to the Senate.

"Governors going to the Senate are an exception rather than a rule," Winter concluded, and some statistics bear that out. Of the 100 members of the Senate, 13 are former governors.

The terms of many leading Democratic governors expire next year, and several will have to decide whether to risk all these odds in a bid for the Senate or take the generally safer route and seek reelection.

Strother said he expects the governors to play a pivotal role in the party's future, even if their best prospects for election to higher office are several years away.

"By 1988," he said, "we're going to find a whole host of Democrats outside the Washington Beltway who are going to be real influential in maybe not turning the party around, but nudging it, if nothing else."