The Tuesday vote will offer an early snapshot of attitudes and energy around abortion, if not a definitive predictor of how those voters will behave in the fall.

“How much of a motivator is it really?” said Dan Sena, a Democratic strategist who guided the House takeover in 2018, of abortion rights, adding that there had recently been signs of improvement for Democrats in some suburban districts. “How does it actually, when it’s by itself, move women, move portions of the electorate? And this will really give us insight and the opportunity to get an answer to that.”

Limited public polling has shown a fairly close if unpredictable race.

“It appears that the ‘Yes’ vote still has the lead, but that has narrowed,” said Mike Kuckelman, the chairman of the Kansas Republican Party. Citing the Dobbs v. Jackson Women’s Health Organization decision that handed control over abortion rights to the states, he continued, “A lot of that is because, I think, the Dobbs decision has incited the pro-choice forces to come out.”