Washington — First the Democrats began copying the Republican computer-age fund-raising techniques. Then they built a television studio to keep up with slick GOP promotional efforts.
Now, it seems, Democrats are even beginning to judge their party leaders by Republican standards. Following the disastrous showing in the presidential elections and desertion by middle America, some Democratic lawmakers are casting about for leadership with style and philosophy that are closer to the GOP.
In this atmosphere Sen. Lawton Chiles, a moderate Floridian, takes the risky move of challenging minority leader Robert C. Byrd of West Virginia, the taciturn, behind-the-scenes specialist who has led Senate Democrats unchallenged since 1977.
His own ''inner voice'' told him to run, Senator Chiles said last week in announcing his last-minute decision. But he also was looking at the Republicans, who had just picked Sen. Robert Dole of Kansas, an articulate and witty party spokesman, as their new majority leader. ''He's good,'' said the Floridian, who dropped a couple of quips in Senator Dole's own droll style.
Meanwhile, House Democrats reelected their top leaders, but they also advanced Rep. Richard A. Gephardt of Missouri, a young moderate, to Democratic caucus chairman. That move symbolizes the coming of age of a new generation of Democratic leaders.
One Democratic aide groused that the new wave of Democrats is fuzzing the differences between the parties. But Representative Gephardt, who seeks more frugal social programs and opposes abortion and school busing for desegregation, makes no apologies.
Democrats ''have to move closer to the middle'' to win back the 51 percent of voters they need, he said in an interview. If that means moving closer to the GOP viewpoint, ''then blurring those lines'' between parties ''is a necessary step,'' according to Gephardt.
The biggest surprise during the post-election Democratic soul-searching is the Chiles challenge, which will be settled Wednesday by secret ballot. For months the Capitol rumor mill carried reports of dissatisfaction with Senator Byrd, but the threat had seemed to die down.
Then came the trouncing at the polls in November. The Democrats picked up two Senate seats, bringing the margin to 47-to-53, but party leaders worry that they may be heading for permanent minority status. ''I think many, many Democrats feel that we have to convince the American people that we are a party that represents middle America,'' Chiles said, declaring himself to be a ''fellow in the middle.''
The folksy and slow-talking Southerner, who won his Senate seat in 1970 by literally walking through Florida, has become known as a coalition builder during the past two years. As ranking Democrat on the Budget Committee, he forged a budget in 1982 that passed the GOP-controlled Senate.
The leadership battle goes beyond political philosophy, since Byrd's voting record is also moderate. Chiles's argument is chiefly that his party needs a ''new face'' at the helm, especially to prepare for 1986, when Democrats are seen as having their last best shot at retaking the Senate during this decade. Twenty-two GOP seats, and only 12 Democratic ones, will be up for reelection.
While Chiles carefully avoided charging that Byrd cannot match the telegenic and forceful Dole, that premise clearly lies behind his candidacy. Chiles said he had received numerous calls from colleagues and was convinced that a ''majority'' was dissatisfied, although he does not claim to have the votes to win.
Byrd, the acknowledged parliamentary wizard of the upper chamber, makes no pretense at being a public persuader. ''I work quietly behind the scenes,'' he said in his response to the unexpected Chiles candidacy.
He also held that he had amassed enough commitments for a victory long before Chiles threw in his hat. Byrd has built his leadership career on caring for the personal needs and schedules of his members, and those past deeds could ensure reelection.
But commitments are not always guarantees in Senate leadership elections. The West Virginian found adjustment to minority status tough after the GOP took over the Senate in 1980. He held last week that the party has now made the transition and become ''accustomed to being the minority.'' As for the call for a Dole-styled leader, he said, ''I don't think the party needs a superstar.''
In the House, the struggle has been far less acrimonious, but Democrats are preparing for a changing of the guard. The feisty and partisan speaker of eight years, Thomas P. O'Neill Jr. of Massachusetts, has symbolized the old-styled politician whose career was based on personal relationships and for whom the most important poll was a stroll down Main Street to talk to shopkeepers.
But Mr. O'Neill is now entering his last term. Upstarts like Congressman Gephardt, a Democrat who is too young to remember Franklin D. Roosevelt and who is at ease with modern technology, are leading toward a peaceful coup de party.
Gephardt has been steadily working within the party structure, heading task forces to search out ''new ideas'' and to reach out to all Democrats, including the sometimes overlooked conservatives. He is widely respected by his colleagues. One Democrat observed that during a private session of feuding senior members, the room became silent when Gephardt spoke.
Clean-cut, serious, and cool-headed, Gephardt won his spot because he ''did his work'' and not by ''cutting deals,'' says Rep. Leon Panetta (D) of California. He has already made a national name for himself by co-authoring the Bradley-Gephardt bill for tax simplification, which has some elements in common with tax reform proposed by the Reagan administration.
As chairman of the 253-member House Democratic Caucus, Gephardt says he plans to continue efforts to include all factions in bimonthly meetings for strategic and legislative planning. The effort may bring his party closer together, but the real goal is to make it more attractive to what he calls the middle 11 percent - the voters that Democrats need to add to what he sees as their solid base of 40 percent of the voters.
''We get identified with spending and elaborate programs and more government and high taxes, and that's not attractive,'' he says. The trick now for the party is to distinquish between good programs and wasteful ones, and ''to try to define a proper government role,'' says Gephardt, who concedes, ''I'm not sure any of us have been very good at articulating what that role should be.''
His party has also lost out on the social issues, he says. ''We have lost some Catholic voters,'' says the congressman, who is Baptist and whose anti-abortion stand fits his largely Roman Catholic St. Louis constituency.