Jimmy Carter, the classic outsider when he came to the White House, is making Washington experience respectable again.

That's the way Rep. Walter Flowers (D-Ala.) sees it. Carter's problems, the five-term congressman says, are the biggest thing he has going for him in his bid to succeed Sen. John J. Sparkman, who is retiring after 42 years in Congress, 32 of them in the Senate.

"Everywhere I go people tell me, 'Walter, experience does matter. Look at what's happening to the president in Washington. He and his people don't seem to know what they're doing," he says.

So Fowlers is doing something a politician wouldn't have dreamed of doing a short time back when "outsiders" were in vogue: he's running as an "insider" unafraid to admit he has Potomac Fever, a guy who boasts about knowing the Washington power game and its players.

"I'm definitely not running against the president," he repeatedly notes with care.

But he is basing his campaign in the Sept. 5 Democratic primary on the insider theme, one that carries an unpleasant message for the Carter White House.

"Good intention won't cure the problems facing America," his campaign brochures proclaim. "Walter Flowers has served in Congress. Walter Flowers has learned firsthand the job out new senator must do."

Flowers isn't alone. Rep. Paul E. Tsongas is using the same insider theme in his race for the Democratic Senate nomination in Massachusetts. He's running as the only candidate in a crowded field with Washington experience. "They can all tell you what they're going to do," his campaign brochures say. "Congressman Paul Tsongas can tell you what he's done.

Two congressmen, of course, don't make a trend. Each has good reasons to play on his experience that have nothing to do with Carter.

In Fowlers' case, it is the wide-open nature of Alabama politics this year.

After dominating the state for 20 years, Gov. George C. Wallace is retiring. So is Sparkman, who represented Alabama in the House for 10 years before coming to the Senate. With the death June 1 of Sen. James B. Allen (D), who was succeeded by his widow, and Sparkman's retirement, Alabama will be without an experience incumbent for the first time in 71 years.

Flowers plays on this by putting two empty chairs before his audiences. But he is finding that experience in Washington can be a double-edged sword.

His chief opponent, former Alabama chief justice Howell Heflin, is going around the state calling Fowlers "part and parcel of that Washington crowd" and asking. "What has that 10 years in Washington brought us?"

His aides follow this up by coyly pointing out a Washington Star "Ear" gossip column which hints that Flowers, whose family stays in Alabama, has a girlfriend in Washington, and that he is involved in the Koreagate scandal. (Flowers admits to nothing more than attending several cocktail parties thrown by Tongsun Park, the South Korean rice merchant accused of influnce-buying in Congress).

Heflin's campaign, however, has had trouble shifting gears since his orginal opponent, Wallace, dropped out of the race. And he appears uneasy attacking Fowlers.

Sen. Maryon Allen is also having trouble with her Washington connection in her bid to serve the remaining two years of her late husband's term.

She's running by not running. Her media advisers have packaged her as Mrs. Jim Allen, the conservative and defense-minded widow of the conservative and defense-minded senator who was Alabama's most popular political figure at the time of his death.

Her staff keeps her in Washington as much as possible. When she does appear in the state, it is largely for ceremonial occasions where she stands little chance of making foolish mistakes or being grilled by opponents or reporters.

But in a series of newspaper, ads, state Sen. Dan Wiley, one of her four opponents, charges. "The real Maryon Allen is different from the image she puts on in Alabama."

He cites a profile of Allen that appeared in The Washington Post. The as quotes freely - if out of context - from the profile, and pictures the senator as an earthy woman who drinks "gigle juice" (white mine) and hasn't had time to mourn her husband's death.

At one point, the profile quotes her as inviting two window washers into her hotel room for a cup of coffee.

"'We had ole time, but if Jim Allen had ever found out I was having coffee with two window washers in my nightgown, he would have killed me,'" it says. "'Can you just see the head of the Alabama Baptist Church if he heard that story?' And she burst into delighted giggles."

In Washington, the profile was viewed as a sympathetic look at a strong woman. "But what looks good in Washington doesn't always look good down here," Lt. Gov. Jere Beasley said. 'It's hurt her here. Not enough to cost her the election, but it hurst her."

"People will vote for me because they loved Jim Allen and they think I'll be like him," Allen says. "I won't disappoint them."