Senators cited conflicting schedules in missing Thursday's talk with Trump.
The Senate will take a procedural vote on Toomey's legislation this week.
The ad will run for two weeks in Ohio starting on Wednesday.
Sen. Joni Ernst is considered a potential Trump VP pick.
Clinton said she was "eager" to speak to authorities.
Trump has promised a lively convention that will stand out from past events.
Sen. Kelly Ayotte said she is "disappointed" Lynch has refused to formally recuse herself.
"I don't think that will be a huge problem," Utah Democrat Misty Snow said.
Timothy Cama 06/30/16 09:42 AM EDT
ClearPath Action Fund is endorsing Reps. Tom Reed and Elise Stefanik.
Rubio has 71 percent support, and Carlos Beruff has 7 percent.