No more costly runoffs.

City Council members joined good-government groups Wednesday to demand an end to the pricey elections sometimes held shortly after primaries.

Tuesday’s runoff for public advocate sparked an uproar, since it cost $13  million to fill an office with a $2.3 million budget.

Council members Gale Brewer (D-Manhattan) and Brad Lander (D-Brooklyn) are pushing a bill that would require voters to determine through a referendum whether they favor “Instant Runoff Voting.”

That would allow people to select a second-choice candidate on primary day, rendering runoffs unnecessary. Runoffs are held if no candidate reaches 40 percent in a multi-candidate primary.

“People . . . would find that their vote actually counted,” Brewer said.