President Trump told reporters Sunday evening that he is not considering firing special counsel Robert Mueller, whose investigation into Russian election meddling has been a constant irritant to the White House. At the same time, however, Trump and his allies are stepping up their campaign to discredit Mueller, who has come under fire from Republicans following reports that several members of his team demonstrated anti-Trump animus.

Investigator Peter Strzok, whom Mueller removed from his team in August, reportedly sent texts to a colleague in 2016 disparaging Trump and saying that Hillary Clinton “just has to win.” Another prosecutor, Andrew Weissman, has drawn criticism as well for his support of the Clinton campaign and an email he sent acting Attorney General Sally Yates praising her for refusing to enforce Trump’s travel ban.