Ex-Energy chief Chu backs Rep. Holt in NJ Senate race

Holt faces an uphill battle to secure the Democratic nomination ahead of the October special election to replace the late Sen. Frank Lautenberg (D-N.J.). The Democratic field includes Newark Mayor Cory Booker, who is the favorite, and fellow Rep. Frank Pallone Jr. (D-N.J.).

Chu, also a physicist, left the Obama administration earlier this year to take a faculty position at Stanford University.

Read the full letter here.