The Justice Department issued subpoenas, a House oversight committee sought interviews and the state opened its own inquiry into a Democratic plan to recruit a spoiler into a Senate race.
A federal judge gave the government until noon on Friday to share which states had received letters trying to enlist them in an effort to find evidence of voter fraud.
Senator Darline Graham, the South Carolina Republican, is struggling to replicate her late brother’s success. Republicans lead in the Florida Senate race and Democrats are up in Minnesota.