Boston city councilors voted overwhelmingly Wednesday to double their terms in office — to four years — and to ban candidates from competing in more than one municipal election at a time.

Councilor Frank Baker, lead sponsor of both measures, said the current two-year term produces low turnout and costs taxpayers $1.6 million per election cycle. Councilors typically spend half their time campaigning instead of working for constituents, said Baker, of Dorchester.

But this is far from a done deal. Mayor Martin J. Walsh must endorse the longer terms for the measure to advance, and it needs legislative approval.

The four-year terms would cover the same period as the mayor’s time in office and would allow councilors to focus on the business of governing, Baker and his colleagues said.

“As we . . . know, there is a very low turnout in these off-year elections when at-large and district city councilor seats are the only contested seats on the ballot,’’ Baker said at the council’s weekly meeting. “Having four-year terms would boost voter turnout by scheduling council elections at the same time as the mayoral election.’’

Councilors voted 12 to 1 to extend the terms, with Council President Michelle Wu the sole opponent. Wu said she’s concerned longer terms would strengthen the position of incumbents and raise barriers for candidates seeking seats.

“If incumbents are able to build up their war chest for an even longer period of time, my concern is that it makes it more difficult for a newer person who [has] to establish credibility and viability,’’ Wu said. “I remember how much pressure there was to raise money when I was first running for office.’’

The council acted unanimously on the measure to prevent candidates from seeking multiple seats in the same city election. It was prompted by the actions of former councilor Charles C. Yancey, who ran for mayor in 2013 while also seeking to keep his District 4 council seat. Yancey got more votes for council than for mayor.

A spokeswoman said the mayor has not made a decision on longer terms or a ban on running for multiple offices.

Walsh may have a political reason for his reticence: Several councilors said a four-year term would help balance power in Boston and put them on a more equal footing with the mayor. In a city with power concentrated in the mayor’s office, an extended term could give councilors a way to stand up to the administration.

The vote to lengthen terms marks the second major action undertaken by councilors in the past six months that would directly affect their own fates. In October, the council voted to give itself a 14 percent raise, to $99,500 a year.

Councilor Timothy McCarthy, who represents Hyde Park and Mattapan, backed four-year terms.

“The most important thing is it gives the elected officials on this body more confidence to try ideas, to challenge the status quo, think outside the box,’’ he said. “And in a two-year cycle it’s difficult to do that.’’

Meghan E. Irons can be reached at meghan.irons@globe.com.