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

Senator John Curtis wrote a letter to the Senate Judiciary Committee calling for a probe 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. 

There was no indication that Republicans, who control the Senate, would act anytime soon.

Committee chairman Chuck Grassley declined to comment, while Senate Majority Leader John Thune told reporters that he did not know enough facts to have a position. 

The open letter marks the latest example of prominent Republicans attempting to create some distance between themselves and 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 running for Senate in Iowa and Michigan, on Monday called for a swift end to the Iran war, an unpopular conflict that has pushed up energy prices and the cost of living, which is Americans’ top concern heading into the midterms.

Republican Paul LePage, the former Maine governor seeking a House seat, also criticized Trump’s deportation of undocumented immigrants on Monday, saying his son’s father-in-law is facing deportation even though he has a work permit. LePage has argued that immigration enforcement should focus on gang members and violent criminals. 

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

Asked about Republicans in key battleground states calling for an end to the Iran war, US Vice President JD Vance told reporters that he had not seen their comments but that it was “completely reasonable that Republicans are going to tailor their campaign messages.”