Federal agents searched a former top Justice Department official’s home and seized records from key Republicans in at least five states linked to Donald Trump’s efforts to overturn the 2020 election, in what were clear signs that authorities are ramping up their investigation of associates of the former president.

Authorities on Wednesday searched the Virginia home of Jeffrey Clark, who was known at the Justice Department to champion Trump’s false claims of election fraud. Agents in recent days also served subpoenas on the Republican Party chairmen of Arizona, Nevada and Georgia, three states that went for President Joe Biden and where Trump allies created slates of “alternate electors” intended to subvert the vote. And Republicans in two other states — Michigan and Pennsylvania — disclosed they had been interviewed by the FBI.