The results of Westbrook’s Republican and Democratic caucuses are in, and so far half of the races will be contested for the dozen official city seats opening up this year.

Incumbent Mayor Bruce Chuluda, a Republican, is being challenged by Democrat Colleen Hilton, a longtime member of the School Committee.

In a three-way race for the two at-large city councilor seats, Mike Lawson, a Democrat, will run against incumbents Mike Foley, a Democrat, and John O’Hara, a Republican. Dale Avenue neighbors, Republican David Tapley and Democrat Victor Chau will compete for the Ward 2 council seat. Planning Board member Paul Emery, a Democrat, is challenging incumbent Republican Lyle Cramer in Ward 3.

So far, incumbent Democrats Brendan Rielly, Ward 1; Suzanne Joyce, Ward 5; and Dotty Aube, Ward 4, are running for City Council unopposed.

For seats on the School Committee, incumbent Ed Symbol, a Republican, will face off with Democrat Martha Henderson in Ward 3. In Ward 4, Republican Gary Rairdon is challenging incumbent Democrat Mary Hall. Emily Serway, a Democrat, is the only candidate for the at-large seat on the board, which is being vacated by Hilton.

City Clerk Lynda Adams, a Democrat, will be seeking a second term, and Republicans have not yet named a challenger.

The last day for residents to take out nomination papers from the city is Sept. 18.