The Dallas Morning News said Cruz "threatens to take the Republican Party to a dark place."
He was the only major candidate who didn't qualify for Saturday's GOP debate.
The Tampa Bay Times calls Sanders's proposals "expensive fantasies."
The letter chides the GOP presidential field for its rhetoric toward Hispanics.
But Cuban said he makes a bigger difference as a private entrepreneur.
Trump previously promised not to bring a suit against Cruz.
O'Malley's March performs on March 13 following his unsuccessful Oval Office bid.
Ted Cruz is in second, 17 points behind, followed by Marco Rubio and Jeb Bush.
Priorities USA Action is spending $5 million on behalf of Clinton.
"Alan Grayson used his status as a congressman to unethically promote his Cayman Islands hedge funds."