The draft-Kennedy-for-president effort in Iowa is beginning to take on the aura of mainstream Democratic Party respectability there.

The reason, according to Roger Owens, a Des Moines lawyer, is simple: "Jimmy Carter has about as much charisma as a garter snake. We've lost one U.S. senator because of Carter, and I'm afraid we'll lose another one unless we get someone else at the top of the ticket." "Someone else" is transparent code for Sen. Edward M. Kennedy (D-Mass.).

Owens is one of six prominent party regulars who have signed a draft-Kennedy fund-raising letter that went out to 10,000 Iowans last week. The length and makeup of the list, party officials say, indicate that support for the draft efforts runs deeper among party regulars than has previously been thought.

The list contains some surprises for president Carter's forces. Owens, for example, is the son of Ed (Soapy) Owens, Carter's foremost supporter in organized labor in Iowa during 1976. Another signer, Rachael Fulton, is a well-liked party activist and wife of former lieutenant governor Robert Fulton.

Other signers are Gertrude McQueen, the former vice chairman of the state party; Harry Smith, one of the state's best-known labor lawyers and a power in Sioux City Democratic circles for two decades; and Mariene Larson, the wife of former state party chairman Cliff Larson.

"Obviously, you don't go after an incumbent president if you are an organization Democrat like I am without a lot of thought," Smith said yesterday. "But we're in trouble in the party, and the only real leader we have to turn to is Ted Kennedy."

The letter, which was mailed last Friday, reads in part: "In 1976 Iowa took the lead in bringing Jimmy Carter to office. We must now act to replace him."

"In Iowa we have tangible results of running with Jimmy Carter," it continues. "You need not be reminded of the losses we suffered in 1978. We lost a senator [a reference to the defeat of then-Sen. Dick Clark], a congressman [Michael Blouin] and majorities in both houses of the legislature."

Iowa has deep symbolic significance for Carter's hope for reelection. He scored his first major victory there in the state's 1976 precinct caucuses, and those caucuses will be his first major test in 1980.

Last March, Iowa also became the home of the nation's first draft-Kennedy effort when a group of labor leaders gathered in Des Moines. Although Carter has trailed the Massachusetts senator by 50 percent to 19 percent in public opinion polls conducted by the Des Moines Register the Committee for an Alternative, as the draft-Kennedy group is called, was thought to include primarily labor leaders until the release of the latter showed otherwise.