There were unexpected political stirrings on the Kansas flatlands when former representative William R. Roy (D-Kan.) filed within hours of last month's deadline to enter the Democratic primary for the seat held by Sen. Nancy Landon Kassebaum (R-Kan.), who is running for her third term.

Roy's entry into the race attracted attention not only for its 11th-hour drama, but also for signaling that Kassebaum, who won 76 percent of the vote in 1984 and is highly favored for reelection, might have a more competitive race this time.

Roy, who represented Kansas's 2nd District in 1971-75, nearly unseated Sen. Robert J. Dole (R-Kan.) in 1974 and ran 12 percentage points behind Kassebaum in his second bid for the Senate in 1978.

But once the lift from his surprise filing wore off, Roy, 65, decided that he did not want to take on the rigors of a statewide campaign again. He withdrew from the race one week after entering. "I erred in getting myself into it," he said.

His exit leaves a lone contender, English teacher Dick Williams, in the Aug. 7 Democratic primary, though Roy's name will stay on the ballot.

Don't think that the Democrats have a lock on primary confusion, however. On the GOP side, Kassebaum faces a challenge from a candidate who filed more than three years ago but who, according to a Kansas Republican Party spokesman, "can't be found."