President Obama has shown a firm commitment to using government to help foster growth. He has formed sensible budget policies that are not dedicated to protecting the powerful, and has worked to save the social safety net to protect the powerless. Mr. Obama has impressive achievements despite the implacable wall of refusal erected by Congressional Republicans so intent on stopping him that they risked pushing the nation into depression, held its credit rating hostage, and hobbled economic recovery.

Mitt Romney, the former governor of Massachusetts, has gotten this far with a guile that allows him to say whatever he thinks an audience wants to hear. But he has tied himself to the ultraconservative forces that control the Republican Party and embraced their policies, including reckless budget cuts and 30-year-old, discredited trickle-down ideas. Voters may still be confused about Mr. Romney’s true identity, but they know the Republican Party, and a Romney administration would reflect its agenda. Mr. Romney’s choice of Representative Paul Ryan as his running mate says volumes about that.

We have criticized individual policy choices that Mr. Obama has made over the last four years, and have been impatient with his unwillingness to throw himself into the political fight. But he has shaken off the hesitancy that cost him the first debate, and he approaches the election clearly ready for the partisan battles that would follow his victory.