Dan Senor, senior national security aide to Mitt Romney, speaks to the press en route to Israel from London on Saturday. Jason Reed/Reuters /Landov hide caption

itoggle caption Jason Reed/Reuters /Landov

Ted Cruz, left, and David Dewhurst shake hands before their Republican Senate debate in Dallas on June 22. LM Otero/AP hide caption

itoggle caption LM Otero/AP

Peoria, Ill., as seen from across the Illinois River. Jeff Haynes/Reuters /Landov hide caption

itoggle caption Jeff Haynes/Reuters /Landov

President Obama waves after speaking at a UPS facility in Las Vegas on Thursday. Nevada is one stop on the president's latest road trip focusing on the economy. Julie Jacobson/AP hide caption

itoggle caption Julie Jacobson/AP

Mitt Romney, accompanied by Rep. Ileana Ros-Lehtinen, R-Fla. (third from right), campaigns Wednesday at a U.S.-Cuba Democracy Political Action Committee event at Miami-Dade College in Miami. Charles Dharapak/AP hide caption

itoggle caption Charles Dharapak/AP