A soybean farmer and former lawmaker will face a member of one of South Dakota's most distinguished political families in a closely watched special election next month to replace Rep. Bill Janklow (search), who resigned after being convicted of manslaughter in an auto accident.

The winner of the June 1 contest between Democrat Stephanie Herseth (search) and Republican Larry Diedrich (search) will serve out the seven months left in Janklow's term.

And no matter who wins, the two candidates will face each other again in the November election for a full two-year term in Congress.

Herseth is a 33-year-old lawyer who was educated at Georgetown University in Washington and worked in the nation's capital. Her grandfather, Ralph Herseth, was governor in 1959 and 1960. Her grandmother was secretary of state in the 1970s. Her father served for 20 years in the Legislature and nearly became governor in a close 1986 race.

Diedrich, 46, spent nearly eight years as a state lawmaker and is former national chairman of the American Soybean Association (search).

Janklow, a Republican who served four terms as governor before being elected to Congress, resigned from South Dakota's lone House seat in January. He served 100 days in jail for the death of a motorcyclist.

The contest is the nation's second special House election this year. In February, Democrat Ben Chandler was elected to Congress after former GOP Rep. Ernest Fletcher of Kentucky became governor of that state.

"I think the Republicans want this election very badly because it might say something about their success in November. On the other hand, the Democrats want it, too," said Terry Robertson, chairman of communications studies at the University of South Dakota.

The House is narrowly divided, with the Republicans holding a 228-205 edge. One representative is an independent but leans toward the Democrats. Replacing Janklow will bring the House to its full 435 members.

The political importance of the contest is apparent from some of the high-level support Diedrich has received.

House Speaker Dennis Hastert made a recent appearance for Diedrich in Rapid City. Senate Majority Leader Bill Frist's national fund-raising committee has given $10,000 to the Diedrich campaign, and Frist will appear with the candidate Saturday in Sioux Falls.

Herseth, who lost a close 2002 House race as a political newcomer against the veteran Janklow, has a better chance of winning this time, Robertson said. She gained attention two years ago and has run a good race by taking the high ground from the start, he said.

"The only thing that's surprised me has been her ability to stay pretty positive for two campaigns," Robertson said. "That's almost unheard of, and I don't know if she'll be able to do that forever."

But Diedrich has at least one advantage: Republicans outnumber Democrats by more than 44,000 in South Dakota, an advantage of nearly 10 percentage points. On the other hand, the state also has 59,000 registered independents.

The race has tightened, according to an independent poll released Tuesday. Herseth led Diedrich 49 percent to 40 percent. Another independent poll in late March showed Herseth's lead at 53 percent to 37 percent.

Diedrich, who has a degree in animal science from South Dakota State University, is counting on voters to give him credit for his legislative and agricultural experience.

"Living in South Dakota and raising a family here and running a business here is part of who I am," he said.