President Trump speaks at a rally at the Charleston Civic Center on August 21, 2018 in Charleston, West Virginia.

President Trump talked about immigration, the upcoming midterm elections and special counsel Robert Mueller's investigation at tonight's rally in West Virginia, but he never once mentioned Paul Manafort and Michael Cohen.

Why this matters: Manafort, Trump's former campaign chairman, was found guilty today on eight counts of financial crimes. This is the first case Mueller brought to trial as part of the investigation into Russian interference in the 2016 US election.

Cohen, Trump's former personal attorney, pleaded guilty in Manhattan today to eight counts. The charges included tax fraud, false statements to a bank and campaign finance violations tied to his work for Trump, including payments Cohen made or helped orchestrate that were designed to silence women who claimed affairs with the then-candidate.

The Cohen investigation was referred to the Southern District of New York by special counsel Robert Mueller. The plea deal does not include cooperation by Cohen, and it is unclear if he will follow through on his previous assertion to friends, according to sources, that he is willing to talk to Mueller.

Trump has repeatedly called the Mueller probe a "witch hunt" that hasn't found evidence of Russian collusion with his campaign, and his allies in and out of the White House say the special counsel should wrap things up.