WASHINGTON (AP) — Republican members of Congress are challenging the deputy attorney general about the political leanings of special counsel Robert Mueller’s investigative team.

The questioning of Rod Rosenstein on Wednesday comes one day after Congress received from the Justice Department derogatory text messages about President Donald Trump from two FBI officials. The text messages ended in late 2016, and the two officials were later assigned to Mueller’s team. That group is investigating potential coordination between the Trump campaign and Russia.

Rep. Steve Chabot, an Ohio Republican, told Rosenstein that the American people deserve an unbiased team.

Rosenstein says there’s a difference between political affiliation and political bias. He says Justice Department officials are entitled to political views but cannot allow them to influence their actions.

Rosenstein also defended Mueller’s investigation, saying he’s seen no good cause to fire Mueller.