Walsh’s chief of staff to leave administration to prepare congressional bid

Daniel Koh, who as Mayor Martin J. Walsh’s high-profile chief of staff helped shepherd the administration through most of its first term, is leaving that post by the end of the month, city officials announced.

The 32-year-old Koh is preparing a run for Congress, according to sources familiar with his thinking, and he is looking at moving back to his hometown of Andover and immediately embarking on a multi-million-dollar fundraising campaign.

Koh declined to specifically address a potential bid, only saying in a statement that it “has been an incredible honor and I am grateful to the people of Boston and Mayor Walsh for the opportunity.”