FRC president says GOP establishment favorite Bill Cassidy can't win in Louisiana.
The two are locked in a tight race in a San Diego swing district.
The former governor tried to rally the conservative base for the vulnerable Kansas senator.
Dan Sullivan (R) leads Sen. Mark Begich (D) by 49 percent to 43 percent in the Chamber poll.
New ads feature testimonials from veterans who have served alongside Iowa GOP Senate hopeful.
A Democratic survey shows Rep. Cory Gardner (R) leading Sen. Mark Udall (D) by 2 points.
Rob Maness (R) is running against Rep. Bill Cassidy (R) and Sen. Mary Landrieu (D).
Rubio last visited the first-in-the-nation primary state in May.
Whether Democrats must pick a nominee impacts race against vulnerable Sen. Pat Roberts (R).
It's the first attack against Orman from a GOP group looking to boost Sen. Pat Roberts (R).