President Barack Obama reaffirmed his commitment Thursday to act unilaterally to change the nation’s immigration laws before the end of the summer, nearly two months since announcing his plan in a Rose Garden speech. “I’ve been very clear about the fact that our immigration system is broken and needs to be fixed,” Obama said. “My preference continues to be that Congress act. I don’t think anybody thinks that Congress is going to act in the short term, but hope springs eternal that after the midterm elections they may act.”