A longtime politician who had touted his pro-infrastructure stance as a reason for developers to support his return to Washington has been defeated in a hotly contested primary.

Boston City Councilor Ayanna Pressley unseated U.S. Rep. Mike Capuano Tuesday in Massachusetts’ 7th Congressional District’s Democratic primary. Capuano, a 20-year incumbent, had been favored to win and was ahead in most polls heading into the primary vote. Pressley won by roughly 17% of the vote, the Boston Globe reports.

The 7th Congressional District is Massachusetts’ only district in which a majority of residents are nonwhite. It includes most of Boston, where Pressley is on the city council, as well as parts of Cambridge and Milton and all of Everett, Chelsea, Randolph and Somerville, where Capuano previously served as mayor.

Capuano spoke at an August Bisnow event in Boston and tried to appeal to the city’s commercial real estate community with his focus on improved transit and affordable housing. Had Capuano won and Democrats taken control of the U.S. House of Representatives, he said he would have chaired either the Committee on Transportation and Infrastructure or the Financial Services Committee.

With no Republican challenger, Pressley is expected to take office in January and be the first woman of color Massachusetts sends to serve in the U.S. House of Representatives.