William J. Janklow has run in six statewide elections here and won five of them, crisscrossing the huge state at the controls of his trusty 1958 Piper Cub. But as he competes in his seventh campaign this fall, winging daily from rural airstrips to small-town tarmacs, even this wily veteran has to concede that he has no idea which way the votes will fly in South Dakota's tight congressional elections.

"Both my race" -- that is, for the state's at-large House seat -- "and the Senate campaign this year are as close as anything we've ever had," Janklow says with a rueful smile. "The tracking polls show both races about one point apart, and none of the candidates is up to 50 percent yet. And you know what's worse? Even my instincts can't tell me who's going to win."

The races are so close, and so well-funded, that virtually every known voter has been identified, targeted and contacted by one or more campaigns.

With the registered voters just about evenly split, the Democrats hit on the idea of turning out new voters, launching registration drives on the Pine Ridge and other Indian reservations.

At first, that move looked brilliant -- by some estimates, the Democrats found 10,000 new registrants, more than enough to provide the winning margin in each race. But the strategy backfired two weeks ago, when charges emerged of registration fraud -- including a few deceased people who signed up to vote again this year -- in some of the heavily Indian counties. The state government and the FBI have launched investigations; nobody knows whether the issue will steer voters away from Democratic candidates.

With the House and Senate up for grabs this fall and South Dakota offering toss-up races for seats in both chambers, this sparsely populated prairie state has become the focus of national attention. Both national parties and dozens of interest groups are shipping in large quantities of literature, advice, commentary -- and money.

The national focus has helped both Democratic incumbent Tim Johnson and his Republican challenger, Rep. John Thune, in fundraising for the Senate race. Each campaign will spend about $5 million, a Texas-sized budget in a state with only 756,000 people. In the race for Thune's House seat, the Republican governor, Janklow, and his neophyte Democratic opponent, Stephanie Herseth, will each spend more than $1 million.

The money is welcome, the candidates say, but the outside "help" is not always appreciated. "For every ad Tim or I put up, the outside groups probably run five or six," Thune complains. "I wanted to control the message right here in South Dakota, but that's impossible now."

Although the House and the Senate races here are too close to call, they have almost nothing else in common. The Senate race has been a nasty, name-calling contest between two intense middle-aged men with almost identical biographies. The competition for the House seat, in contrast, pits two contenders so different they might be from different planets.

The 63-year-old Republican, Janklow, is a plain-spoken, gray-haired veteran who loves to remind audiences of the complex political gambits he employed to get a dam built in this county or win federal funds for a "four-lane" -- that's South Dakotan for "expressway" -- in that one.

After four terms in office, Janklow is the nation's longest-serving governor. One of the abiding mysteries of this fall's campaign is why a man who has dominated his state for so long would want to become a junior member of a 435-seat assembly in Washington.

Conventional wisdom in both parties is that Janklow got into the GOP primary mainly to block his longtime adversary, former senator Larry E. Pressler, from winning the nomination. While he achieved that result, Janklow himself has a different explanation for his entry. Sept. 11, 2001, prompted him to think about national office, he says, and the national GOP pleaded with him to run to keep the South Dakota House seat on the Republican side of the aisle.

If Janklow is the worldly-wise grandpa of South Dakota politics, his 31-year-old Democratic opponent, Herseth, a graduate of Georgetown University and its law school, is the perky, idealistic granddaughter.

Where Janklow is rumpled and scruffy, Herseth is fashionable and picture-perfect. While Janklow is famously blunt -- he likes to remind voters that he changed the name of the state's "correctional facility" to "prison" -- Herseth is constantly cautious, on guard against saying anything that might be construed as "liberal."

"That's not a term that is respected here," she notes.

When a voter at a veterans' hall lobbed an easy softball question at Herseth -- "Would you repeal those tax cuts for billionaires so we can steer the money to veterans?" -- she refused to take a swing. Rather, the candidate launched into a complex 14-minute response, noting that "I have to be careful when it comes to tax cuts." She supports abortion rights, but doesn't say that. Her standard response on the issue is "Like most people, I want to make it as rare as possible."

Herseth had trouble raising money at first because the national political establishment figured Janklow was unbeatable. In fact, the young newcomer has been running even, or slightly ahead, from the first days of the campaign. Both candidates offer the same explanations for this unexpected turn of events.

One factor is "Janklow fatigue." After 16 years in the office, the pull-no-punches governor has made enemies as well as allies all over the state. Herseth, in contrast, seems to win friends easily with her cheery smile and youthful energy.

Herseth says being female "is an advantage, because we haven't sent a woman to Congress yet." And she makes much of the South Dakota tradition of giving the state's one House seat to an unknown thirtysomething. Several giants of local politics -- including Johnson, Thune, Pressler and Senate Majority Leader Thomas A. Daschle -- all won election to the House when they were about Herseth's age.

For tactical reasons, the House candidates have eschewed negative ads.

The Senate race, in contrast, has turned into a nasty exchange of attacks on TV and radio.

Johnson, the Democrat, has hit Thune hard on Social Security and education issues. Thune has responded with a tough but witty attack on Johnson for taking foreign trips paid for by industry associations. In the radio ad, an airport PA announcer intones, "Senator Johnson, your junket -- er, trade mission -- is ready for departure."

Thune says he thought hard about running for the gubernatorial seat that Janklow is vacating. But he was personally recruited for the Senate race by President Bush and other GOP leaders, who saw South Dakota as a likely spot to knock off a sitting Democratic senator.

The president, accordingly, has been here twice to campaign for the Republicans, and he is expected back once more. But Bush's visit in August was a downer for the Thune campaign, because the president refused, on budget grounds, to offer any new financial aid for drought-stricken Dakota farmers. That rejection undermined Thune's claim that his White House connections will work to South Dakota's advantage.

While Thune plays up his White House connections, Johnson emphasizes how closely he works with "my good friend Tom Daschle." Indeed, the Senate race between Thune and Johnson sometimes sounds like a proxy battle between Bush and Daschle, both immensely popular in this divided state.

In addition to TV ads by the bushel, all the outside money pouring into South Dakota's pivotal congressional contests is also paying for a lot of polling. Unfortunately, the daily tracking polls on both sides keep coming back with the same result: Both races are basically tied. And not even a political sage of the stature of Bill Janklow is likely to know the result until extremely late on the evening of Nov. 5.

South Dakota Gov. William J. Janklow and Stephanie Herseth chat at a debate at the South Dakota State Fair this summer in Huron.