WASHINGTON A Georgia-based probe into whether former Republican President Donald Trump and others illegally sought to overturn his loss in the state's 2020 presidential election has expanded into activities outside of Georgia, the Washington Post reported on Friday.

Fulton County's prosecutor has broadened the two-year-long investigation to include Trump's campaign "hiring two firms to find voter fraud across the United States and then burying their findings when they did not find it," including issuing a subpoena to one of the companies, the Post reported, citing two people with knowledge of the probe.

Willis has publicly indicated that her office is looking at whether Georgia’s Racketeer Influenced and Corrupt Organizations (RICO) statute would apply and whether efforts to overturn Trump's loss in the southern U.S. state were a far-reaching criminal scheme, according to the Post.

A spokesperson for the Fulton County district attorney's office declined to comment on the report.

Willis, a Democrat, has said charging decisions are expected this summer.

As part of the probe into Trump and his allies efforts, Willis's office has sought information from Simpatico Software Systems and Berkeley Research Group about their actions in Georgia and other U.S. states, the Post said.

The companies declined to comment to the Post as did Willis' office and representatives for Trump.

Trump has denied any wrongdoing and called the investigation, along with others he is facing, politically motivated. The Department of Justice is also investigating Trump's role in efforts to overturn his 2020 loss to Democrat Joe Biden.

A number of individuals under investigation in the Fulton County probe have accepted immunity deals, court records showed last month.

(Additional reporting by Joseph Ax; writing by Susan Heavey; Editing by David Gregorio)