Washington is a city of sideshows, full of people who consider it their job to create distractions from the nation’s most serious problems. Politicians would rather argue about nonexistent scandals or plot to undermine each other’s programs than come up with ways to create jobs or elevate the hopes of the next generation.

President Obama needs to change the subject to have a successful final term, and he announced on Wednesday, in forceful terms, that he intends to do just that. In a speech in Galesburg, Ill., he said his highest priority for the next 1,276 days would be rebuilding a middle class that has been battered by globalization, technological change, and the concentration of wealth at the highest levels.

“Washington has taken its eye off the ball,” he said, “and I am here to say this needs to stop.”

The fundamentally American idea that hard work leads to success, he said, has been undermined by an inattention to education and decades of government policies that favored only the rich. While income of the top 1 percent nearly quadrupled from 1979 to 2007, there has been almost no change in the typical family’s income.

And he wasn’t shy about pointing directly at Republicans who have made the problem worse by cutting spending when the economy needs new investments and by damaging the nation’s credit by threatening not to pay the government’s bills. The “meat cleaver called the sequester,” he said, has cost jobs, hurt the military and retarded progress in science and medicine.