Republican senators are asking Secretary of State Rex Tillerson to investigate claims that U.S. taxpayer money is being used to back left-wing billionaire George Soros' political meddling and similar efforts overseas.

A letter sent Tuesday asked for a probe into how U.S. funds are being used by agencies such as the United States Agency for International Development (USAID) to back left-wing political groups in other countries. 

Sen. Mike Lee, R-Utah, one of the co-signers, even said foreign officials and political leaders have come to him with "reports of U.S. activity in their respective countries."

He said in a statement: "This includes reports of diplomats playing political favorites, USAID funds supporting extreme and sometimes violent political activists, and the US Government working to marginalize the moderates and conservatives in leadership roles. ... This sort of political favoritism from our missions around the world is unacceptable.”

The letter to Tillerson also was signed by Sens. James Inhofe, R-Okla.; Thom Tillis, R-N.C.; David Perdue, R-Ga.; Ted Cruz, R-Texas; and Bill Cassidy, R-La. It followed a letter in February from GOP lawmakers asking about whether U.S. tax dollars have been used in recent years to fund Soros-backed projects in the small, conservative-led country of Macedonia.

In particular, USAID funding to Soro’s Open Society Foundations in Macedonia sparked concern that the U.S. Embassy has been taking sides in the country’s fiery political fights. The group's stated goal is “to build vibrant and tolerant democracies whose governments are accountable to their citizens” but critics claim it's a front for Soros’ political maneuverings.

The USAID website shows that between 2012 and 2016, USAID gave almost $5 million in taxpayer cash to FOSM for “The Civil Society Project,” which “aims to empower Macedonian citizens to hold government accountable.” USAID’s website links to www.soros.org.mk, and says the project trained hundreds of young Macedonians “in youth activism and the use of new media instruments.”