Donald Trump on Friday said he would not debate Vermont Sen. Bernie Sanders because it would be “inappropriate” to square off against the candidate who currently trails Hillary Clinton in the Democratic primary fight.

“Based on the fact that the Democratic nominating process is totally rigged and Crooked Hillary Clinton and (Debbie) Wasserman-Schultz will not allow Bernie Sanders to win, and now that I am the presumptive Republican nominee, it seems inappropriate that I would debate the second-place finisher,” Trump said in a statement.

Trump also said news networks “are not proving to be too generous to charitable causes,” which he previously had said would be a goal of debating Sanders. The two populist candidates had floated the idea of debating each other throughout the week.

Sanders has been trying to debate Clinton ahead of the California primary on June 7, but she, too, declined.