BOSTON (AP) — Boston Mayor Marty Walsh's chief of staff is stepping down to run for the Congressional seat being vacated by Democrat Niki Tsongas.

The Lowell Sun reports (http://bit.ly/2uYNHs1 ) Daniel Arrigg-Koh will leave his post in two weeks to focus on his campaign. The 32-year-old is a native of Andover, which is in the third congressional district that covers parts of northern and center Massachusetts, including the Merrimack valley communities of Lowell, Lawrence and Haverhill.

Koh's father, Dr. Howard Koh, is a former state public health commissioner and assistant secretary of the U.S. Department of Health and Human Services. His grandfather, Kwang Lim Koh, was acting ambassador to the U.S. for South Korea.

The 71-year-old Tsongas, who was first elected in 2007, announced earlier this month she won't seek re-election in 2018.

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Information from: The (Lowell, Mass.) Sun, http://www.lowellsun.com