Mueller is leading the probe into whether Russia interfered in the 2016 presidential election with help from Trump campaign aides. So far, four Trump associates have been charged in Mueller's investigation; three have pleaded guilty to lying to the authorities.
Trump has repeatedly referred to Mueller's team as "13 angry Democrats," although Mueller is a Republican. Mueller was appointed by Trump's deputy attorney general, Rod Rosenstein.
On Tuesday, Trump tweeted: "The 13 Angry Democrats (plus people who worked 8 years for Obama) working on the rigged Russia Witch Hunt, will be MEDDLING with the mid-term elections, especially now that Republicans (stay tough!) are taking the lead in Polls. There was no Collusion, except by the Democrats."
Later Tuesday morning, Trump appeared to be taking guidance from some of his advisers and supporters to heart, saying he needed to focus more of his attention on issues important to Americans and less on the Russia investigation.
"Sorry, I've got to start focusing my energy on North Korea Nuclear, bad Trade Deals, VA Choice, the Economy, rebuilding the Military, and so much more, and not on the Rigged Russia Witch Hunt that should be investigating Clinton/Russia/FBI/Justice/Obama/Comey/Lynch etc.," he tweeted.