The network is making its most aggressive intervention yet into the 2016 cycle.
The pitch comes after a confrontation over ethics violation allegations against Grayson.
Locked in a tight race in Illinois, the two have released ads in the last two days.
Johnson accused Democrats of trying to "politicize" his comments.
"He wants us to be just another country," Carlos Beruff said.
Sen. Ron Johnson used a 9/11 story to highlight the importance of voting.
"Why do you perpetuate these lies this way?" Grayson asked.
The donor, an old friend of Rep. Patrick Murphy, pleaded guilty to assaulting his wife.
The former House Speaker has repeatedly criticized Cruz.
Sen. Bob Menendez was indicted last year on corruption and bribery charges.