— COLUMBUS, OhioThe first prime-time debate of the Ohio gubernatorial primary opened Thursday night with the bland choreography typical of the genre — opening statements, a question on the state's pension fund, a question on the Cincinnati waterfront — and within twenty minutes had collapsed into the kind of personal exchange that campaign veterans here said they had not seen in a decade.

By the time the moderators called the candidates back to a question on infrastructure, the front-runner had been twice accused of misrepresenting her own record on transit funding, the second-place candidate had been called "a creature of the lobbyist class," and the third candidate, an obscure mayor from the state's southeast, had quietly become the most-clipped figure on social media.

"This is what happens when the polls tighten," said Howard Marsh, a longtime Ohio political observer who watched the debate from the press balcony of the Ohio Theatre. "Civility is a luxury good."

Substantively, the candidates clashed on three principal axes: the structure of the state's income tax, the role of state troopers in immigration enforcement, and what one of them called "the unfinished business" of the previous administration. The exchanges were sharper than the policy differences themselves — all three are, by the standards of their party, occupants of roughly the same lane — but the tone, several party officials said afterward, was likely to harden through the spring.

The primary is scheduled for early May. Polling, sparse and of variable quality, suggests a three-way race in which the front-runner's lead has narrowed by half over the last month. A second debate is scheduled for late April in Cleveland.