The race for the Boston City Council continues to percolate as the field shifts ever so slightly with summer bearing down on the city.

The at-large field has thinned to a group of five, with Dorchester’s Annissa Essaibi George emerging as the lone challenger to the four entrenched incumbents: Stephen Murphy, Ayanna Pressley, Michael Flaherty, and Michelle Wu as Bryan Fuller of South Boston, withdrew from the race last week.

Fuller, a first-time candidate and the fastest American to row across the Atlantic, cited a lack of institutional support and fundraising shortcomings for his withdrawal. “My message was really resonating with voters,” Fuller said in a statement, adding, “while it did not come together this time, I will be more prepared in two years because of this experience.”

In District Four, which includes parts of Mattapan, Dorchester, Hyde Park, and Jamaica Plain, political newcomer Andrea Campbell has kept up her fundraising momentum with the recent support of the Massachusetts Women’s Political Caucus Political Action Committee. Campbell, in turn, has opened her campaign headquarters in a Fields Corner storefront. City Councillor Charles Yancey has picked up the pace of his campaign, both in-person and online, as he aims to thwart the efforts of Campbell, Jovan Lacet, and Terrence Williams to take away the Council seat he has held for 33 years.

The race in District Seven, which includes Roxbury, parts of Dorchester, Jamaica Plain, and the South End, remains the most crowded ahead of the fall election with five candidates looking to defeat sitting Councillor Tito Jackson. The field features a line-up of familiar names: former state Rep. Althea Garrison, TOUCH 106.1 co-founder Charles Clemons, pro-life advocate Roy Owens, Kevin Dwire, and community activist Haywood Fennell Sr. All have previously run for the seat. Still, this year’s race falls short of the energy of the 2011 campaign when a field of 16 candidates vied to fill the seat vacated by Chuck Turner after he was sentenced to prison for bribery.

In District Five, it’s incumbent Timothy McCarthy and challenger Jean-Claude Sanon, who is facing a fine from the Office of Campaign and Political Finance for not filing finance disclosures during a previous run for office. OCPF has sent a fifth notice to Sanon, and if he does not pay the $200 fine – plus interest – he will have to answer to a collection agency. The sum had not been paid as of press time on June 10, OCPF confirmed to the Reporter. The initial fine was $1,200 but that was reduced to $200 after an appeal. The penalty must be paid from Sanon’s personal funds.

A handful of incumbent councillors face no challengers: Sal LaMattina of Charlestown and East Boston, Bill Linehan of South Boston, Matt O’Malley of West Roxbury and Jamaica Plain, Josh Zakim of the Back Bay, and Mark Ciommo of Allston Brighton.