WASHINGTON — The Democratic National Committee on Thursday postponed its presidential convention because of the coronavirus, moving it from mid-July to mid-August, and making it the largest political event to be upended by the public health crisis sweeping the country.

The convention will still be held in Milwaukee, as planned, the week of Aug. 17, officials said — a week before Republicans plan to gather in Charlotte, N.C., to renominate President Trump. The adjacent dates mean that both parties will be using expert health data from the same time frame to assess the safety of bringing together thousands of people at one event — and, ultimately, deciding whether the benefit of staging the conventions outweighs the medical risks.