His entry into the Indiana race represents a major recruiting win for the Democrats.
Kirk said Trump doesn't have "the temperament or judgment to be our commander-in-chief."
Tim Devaney 07/07/16 04:42 PM EDT
The group called Rubio "a strong advocate for the rights of law-abiding gun owners."
Sen. Kirk said his split with Donald Trump "pretty clearly demonstrated" his independence.
The GOP senator still holds a cash advantage.
The campaign uses animated GIFs from the movie "Zoolander."
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.