Portland voters can expect at least two hotly contested races on the city ballot in November – a four-way mayoral race and five-way race for the District 3 seat on the City Council.

In all, six seats – the mayor’s post, two other council members and three on the board of education – are up for grabs this fall. On Wednesday, Portland’s city clerk completed the process of determining which prospective candidates submitted enough valid signatures to qualify for the ballot.

Three of the six seats are unopposed. Neither incumbent City Councilor Pious Ali nor incumbent school board members Roberto Rodriguez and Anna Trevorrow face any declared challengers for their respective at-large seats.

All eyes will undoubtedly be on the mayoral race, the city’s third since switching in 2011 from a ceremonial mayor appointed by fellow members of the council to a mayor elected by voters citywide.

Portland’s mayor is a full-time position that currently pays about $73,000 a year and carries a four-year term, which is one year longer than the terms of other councilors and one year longer than school board terms. However, the mayor has no executive control over city staffing or operations – those duties belong to the city manager.

The mayor’s duties include working with the councilors to establish citywide goals and implementing those goals through the city manager. The mayor is also tasked with providing comments on city budgets, giving an annual “State of the City” address, and advocating for the city at the state and federal levels.

Incumbent Ethan Strimling, 51, is completing his first term and is running for re-election.

He is being challenged by City Councilor Spencer Thibodeau, a 31-year-old real estate attorney currently serving his second term on the council representing the West End.

Kathleen Snyder, a 49-year-old former school board member and current executive director of an educational nonprofit, also is running for mayor and posted competitive fundraising numbers in July.

The fourth candidate to qualify for the ballot is Travis Curran, a 33-year-old server who has volunteered with Neighbors in Need to feed the homeless and has organized fundraisers and other events.

Thaddeus St. John, the 27-year-old owner of the South Portland winery, Lincoln & Main, turned in his nomination petitions, but he did not have enough valid signatures to qualify.

The race for the District 3 City Council seat, which represents areas including Libbytown and Stroudwater, also will be competitive. Incumbent Brian Batson decided not to seek re-election after serving one term.

The five candidates for the District 3 seat are:

• Former City Councilor Edward Suslovic, a 59-year-old sustainable development and environmental finance consultant. Suslovic, who also is a former state legislator, served three terms on the council before he lost the same seat to Batson in 2016.

• Tae Chong, 50, the manager of social enterprise and workforce development for Catholic Charities of Maine. Chong is a former school board member, a founding board member of the Friends of Portland Adult Education, and has served on boards for the United Way, University of Southern Maine and Maine COmmunity Foundation;

• Andrew Graham, 67, a retiree who is the acting executive director of Kinonik, a nonprofit that archives significant 16mm films from 1900 to 1960. He is also a founding president of Creative Portland, board president of SPACE Gallery and founding president of the Friends of Capisic Pond.

• Lalah “Layla” Kargar, 33, the publisher and owner of Incomer Magazine, owner of Drifters Gallery and agent to Paul Monroe, and the president and owner of Express Solutions/Portland Payments.

• And Andrew Volk, 35, the owner of the Portland Hunt + Alpine Club, Little Giant and Giant who says he’s been active in local efforts to support the Affordable Care Act and raising the minimum wage.

There is a two-way race for District 3 school board seat, which was left open when incumbent Laurie Davis decided not to seek reelection.

That race features 39-year-old Adam Burk, who works in leadership and community development and has two children, ages 2 and 6, versus 66-year-old Sam Rosenthal, a retired engineer.

The mayor’s race will be decided through ranked-choice voting, which allows voters to rank candidates by preference.

In a ranked-choice election, voters rank the candidates in order of preference. If no one wins a majority after the first tally, election officials eliminate the last-place finisher and redistribute that candidate’s votes based on each voter’s second-choice ranking. This process continues – with non-viable candidates being eliminated from the bottom up and their votes reallocated – until someone hits the threshold of 50 percent plus one vote.

The other council and school board races will be determined by a traditional plurality system, in which the winner is the person who receives the most votes.