A Republican US senator on Tuesday called for an investigation into the ways that President Donald Trump’s family is profiting from his time in office, saying the perception that they are exploiting their position is undermining trust in the government.

Senator John Curtis wrote a letter to a Senate panel to call for an investigation into businesses owned by Trump’s eldest son, Donald Trump Jr., and payments by a Russian oligarch for his wedding celebrations in the Bahamas this year. Congressional Democrats launched an investigation last week into the wedding payments.

The open letter marks the second time in two days that prominent Republicans have broken with the increasingly unpopular president, six weeks from midterm elections in which his party is defending thin majorities in the US Congress.

Republicans Ashley Hinson and Mike Rogers, who are both running for Senate, on Monday called for a swift end to the Iran war, trying to distance themselves from the unpopular conflict that has pushed energy prices higher and driven up the cost of living, Americans’ top concern heading into the midterms.

But unlike Rogers and Hinson, Curtis, of Utah, is not up for reelection until 2030.

Reuters/Ipsos polling this week showed Trump’s public approval at its lowest point ever, with voters’ support for electing Republicans in the November 3 midterm elections also weakening.

‘Legitimate Questions’

In a letter to the Senate Judiciary Committee, Curtis urged the panel to investigate presidential family relationships and their possible leverage by domestic and foreign entities, including wedding festivities worth hundreds of thousands of dollars for Trump Jr. paid by Russian oligarch Umar ​Kremlev.

Curtis also raised questions about Trump Jr.’s business ventures, including crypto promotion, real estate deals, prediction market platforms and more as his father controls the White House.

“These reports raise legitimate questions about foreign access to members of a sitting president’s family and whether such relationships can create actual or perceived expectations of favorable treatment,” he wrote. “They also may create expectations of a returned favor that would not be in the best interests of the American people or our allies, and could even create national security vulnerabilities.”

Trump last week said that his son is paying back​ Kremlev but offered no other details, while a person familiar with the situation had told Reuters that Trump Jr. planned to reimburse the Russian.

The Trumps have defended their family business dealings while Trump is in office and denied any conflicts of interest, pointing to a trust managed by Trump Jr. and Eric Trump.

Representatives for Donald Trump Jr. could not be immediately reached for comment.

Curtis pointed to previous congressional investigations into former President Joe Biden’s son, Hunter Biden, and said there should be equal standards, regardless of political party.

“The country should not have to accept one standard for the family of a Republican president and another for the family of a Democratic president,” Curtis wrote. “Nor should congressional oversight begin and end when control of the White House changes hands.”

Representatives for Hunter Biden could not be immediately reached. The younger Biden, who has worked as an artist, lawyer and investor, has faced years of scrutiny from Republican lawmakers, particularly over his foreign business dealings. He has denied any wrongdoing.

(Reporting by Susan Heavey; editing by Scott Malone and Deepa Babington)