BALTIMORE — Virginia Gov. Bob McDonnell (R) will not address the House Republican retreat in Baltimore on Saturday because he has declared a state of emergency in his state in advance of a possible snowstorm.McDonnell, who delivered the Republican rebuttal to President Barack Obama’s State of the Union address Wednesday, was scheduled to speak to the Republican Conference on Saturday morning. A McDonnell spokeswoman confirmed Friday that the new governor would remain in the state to manage the possible snow emergency.