The challenge for Kansas Democrats, though, is that Ms. Kelly is not the only alternative for dissident Republicans or unaffiliated voters uneasy with Mr. Kobach and Mr. Colyer.
Greg Orman, a wealthy businessman who ran as an independent against Senator Pat Roberts in 2014, is also seeking the governorship this year, again as an independent. Having already spent $650,000 of his own money, Mr. Orman threatens to siphon votes away from Democrats, potentially allowing Mr. Kobach or Mr. Colyer to win the governorship with only a plurality.
His candidacy has infuriated Democrats, who are stung in part because they effectively undid their nominating process in 2014 to let Mr. Orman serve as their de facto standard-bearer against Mr. Roberts.
“It’s all about ego,” Ms. Sebelius said of Mr. Orman’s candidacy. She said there had been “a whole lot of people approaching Greg saying, ‘Do not do this’ and ‘All you can do is be a spoiler.’”
Ms. Sebelius said the effort to push Mr. Orman out of the race would intensify, but if he does not leave, Democrats would have to “Jill Stein him” — a reference to the Green Party presidential nominee who drained votes from Hillary Clinton in 2016 — and warn that “a vote for him is just a vote for Kobach.”
Asked about the criticism that he would simply assure a Republican victory, Mr. Orman said, “Votes aren’t the property of the parties, they belong to the people.”
At least one Republican seemed confident about the source of Mr. Orman’s support.
“A liberal independent jumping in?” said Mr. Kobach, with evident delight. “I think he will probably take votes from the Democrats.”
As for his state’s “throw the bums out” impulse, Mr. Kobach said he would be even more of a conservative than Mr. Brownback. “It is time for a change,” he said. “But the time for a change doesn’t have to be in a leftward direction.”