Julian Zelizer is a professor of history and public affairs at Princeton University. He is the author of "Jimmy Carter" and "Governing America."

(CNN) -- August is going to be a crucial month for President Barack Obama.

As the 113th Congress takes its recess, legislators will be returning to their states and districts to hear from constituents.

The stakes are particularly high for Obama and Democrats, who have one last chance to sway the House Republicans before two hugely important issues are resolved: the immigration bill and the budget.

As politicians in both parties begin to prepare for the 2014 midterms and think about the 2016 elections, this fall might be the last real opportunity for the president to win congressional support for these big measures....