The D.C. Council on Tuesday began working on a bill that would eliminate its power to vote on multimillion-dollar contracts negotiated by the mayor.

The legislation would prohibit council members from voting on large contracts bid on by some of the city’s biggest contractors — and political contributors. But the bill would also tilt the city’s balance of power in favor of the mayor.

The idea, which has been around for three years, gained momentum last year when council members Jack Evans (D-Ward 2) and David Grosso (I-At Large) introduced legislation following a series of resignations and disciplinary actions against council members for interfering in city awards.

Evans and Grosso — along with D.C. Attorney General Irvin B. Nathan — argued in a hearing Tuesday that the bill may be the only way to remove an inherent conflict of interest in having council members with scant contracting knowledge make the final call on awards that often affect political donors.

“Yes, it serves as a check and balance on the mayor,” Evans said. “But does that override the enormous concern that exists in the city today that people who contract with the government are buying the contracts by campaign contributions? I think not.”

Nathan, testifying on behalf of Mayor Vincent C. Gray’s (D) administration, went further:

“Members of this council . . . who have either a personal interest in a transaction or a constituent’s interest in a transaction have engaged in politicizing or attempting to either void or delay contract approvals,” Nathan said. “The mayor has continuously urged this council to sever the corrosive ties between district contracts and political donations, and to eliminate the perception that politics . . . plays any role in [contract] awards.”

Although a majority of council members have signed on as sponsors, not everyone appeared convinced. Council Chairman Phil Mendelson (D) who will determine whether the measure moves forward, said the criticism he hears most often from city residents is that District business remains opaque. He said he worried that eliminating the council’s public voting on large contracts and its production of contract documents for public review could remove voters’ only view of many decisions.

Government watchdogs and some city contractors also raised concerns, saying that taking award decisions out of public view would do more harm than good — and come at a time when the Democratic mayor’s relationship with the city’s former top contractor remains the subject of a federal investigation.

“It is the single greatest governing tool you have,” said Ramesh Butani, president of HRGM Corp., which has contracted with the city. Butani said every month he reads every contract that the council approves.

“Without the light that this rule brings forth, we will all be like mushrooms, kept in the dark and fed nothing but ‘you can take our word for it,’ ” he said.

Council member Marion Barry (D-Ward 8), who was censured last year for taking thousands of dollars in cash payments from contractors with business before the city, called the proposed measure “pro-corruption.”

The council’s authority to review contracts was set under the control board that Congress established to oversee the city when Barry was mayor.

“It’s an invitation to corruption, anytime you put power in one person’s hands,” Barry said. “If you take the council out of it, you invite opaqueness, shenanigans, mischief . . . everything we’re opposed to.”

Grosso said that the city’s contracting offices have become more professional and that reducing the number of politicians who could influence city contracts would do the most to restore public trust in the District government.

“I think the time has come for us to step up and take this brave step,” Grosso said. “It’s rare to have . . . members of a legislative body remove themselves from a certain power like this.”

Mendelson is also pursuing another major change, a bill barring anyone who contributes to a District politician from pursuing a contract with the city.