A contentious decision to allow Mayor Michael Bloomberg to run for a third term was the hot-button topic Monday in a debate for the powerful office of city comptroller.

Former Gov. Eliot Spitzer and Manhattan Borough President Scott Stringer, in a fiery encore to their heated first debate, exchanged verbal haymakers over Bloomberg’s legacy, as Spitzer seized upon Stringer’s support of the 2009 decision to overturn term limits and let the mayor run again as a way to question his judgment.

“The reason why we had a third term is that the political establishment, with Scott’s support and participation, gave the mayor a third term,” said Spitzer, who criticized the independent mayor’s recent handling of issues including community policing and zoning laws.

Stringer allowed that he supported the change in the term limits law, saying he believed “elections are about democracy.” He later campaigned for Bloomberg’s opponent.

Spitzer, who resigned as governor after admitting to his scandal, and Stringer, a former state assemblyman, frequently talked over each other during the hour-long debate and scolded each other for interrupting.

Stringer appeared set to run unchallenged for the Democratic nomination only to find himself cast as the underdog when Spitzer unexpectedly jumped into the race last month and quickly moved to the top of the polls. Stringer repeatedly hammered the former governor for resigning “in disgrace” and for opting out of the city’s campaign finance system to instead self-finance his comeback bid.

“I may not be the celebrity candidate,” Stringer said. “But I have never embarrassed my constituents, not for one minute, and I never will.”

Discussions of the obligations of the comptroller position, which include auditing the city’s contracts and overseeing its workers’ pension system, were frequently drowned out by the personal attacks. But a few lighter moments unexpectedly appeared near the end of the debate, which was broadcast live on the NY1 cable news station.

In a lightning round, both men admitted they had never used a CitiBike, from the city’s bicycle sharing program, or eaten a cronut, the trendy doughnut-croissant hybrid.

Spitzer said he once voted for a Republican but did not say whom. Stringer, who lives on Manhattan’s liberal Upper West Side, answered the question in mock horror, gasping, “No.”

The showdown, which was sponsored by the city Campaign Finance Board, was the first official debate of the year. The two men participated in an unofficial debate on Friday.

The primary is scheduled for Sept. 10. The winner can expect to face Republican and other candidates in the general election Nov. 5.

(AP)