CHICAGO — Republicans are showing up on and off the stage at the Democratic National Convention to urge their peers to support Vice President Kamala Harris for president over former President Donald Trump.

A mayor in a battleground state, a former Trump voter, and a former Trump White House official have already addressed the convention to explain why they cannot support the former president’s return to the White House as they seek to appeal to those in the middle of the political spectrum. More high-profile Republicans will take the stage on Wednesday.