WASHINGTON -- President Obama's State of the Union address on Tuesday is about more than the final three years of his presidency. Its purpose should be to influence the next decade of American political life and begin shaping the post-Obama era.

For the first time since his early days in office, Obama has the philosophical winds at his back. He may be struggling with his approval ratings, but the matters the president hopes to move to the center of the national agenda -- rising inequality and declining social mobility -- are very much on the nation's mind.

The days leading up to Obama's best chance to redirect the country's conversation brought two important signals that the tectonic plates beneath our politics are shifting. One was a striking Pew Research Center poll showing that on issues related to economic and social justice, Democrats and independents are on the same page while Republicans find themselves isolated.

The other was a speech by Sen. Charles Schumer, D-N.Y., at the Center for American Progress. One of his party's sharpest strategists, Schumer is a pragmatic sort of liberal with a lifelong mistrust of ideologues. But his address was a populist rallying cry, calling on Democrats to embrace "a renewed and robust defense of government" in the face of the tea party's challenge.

Democrats, he said, needed to make "the decline in middle class incomes, the slow-growth of good-paying jobs, and the idea that too little of our productivity benefits wages" central concerns in the coming years. Arguing that his party "accepted too easily the primacy of the deficit" in its approach to policymaking, Schumer praised Sen. Elizabeth Warren, D-Mass., the bane of the world of high finance, for being "one of the first to sound the alarm bell" on the deterioration of middle-class living standards. And he assailed the "plutocrats" who finance a tea party movement that often works against its members' interests.

Schumer never forgets that he has constituents on Wall Street and went out of his way to say that Americans "don't mind if incomes of people at the top go up 20 percent as long as theirs go up 3 to 4 percent." But it says something about his political intuitions that he cited Warren and offered a tough critique of the economy's shortcomings.

The Pew survey released on the day Schumer spoke ratified his instinct. It should also worry Republicans who emerged as outliers on key economic questions. Asked how much government should do to reduce poverty, 67 percent of Democrats and 56 percent of independents said it should do "a lot." Only 27 percent of Republicans said this.

There was a similar contrast in how Republicans and everyone else viewed wealth and poverty. Pew asked respondents if the wealthy got that way primarily because they "worked harder than others" or because they "had more advantages." Republicans ascribed wealth to hard work by a margin of 57 percent to 32 percent. But among Democrats, only 27 percent pointed to hard work, while 63 percent highlighted the advantages the wealthy enjoyed. Independents split in the same direction: 37 percent said hard work, 52 percent said the rich had more advantages.

As for why individuals were poor, 51 percent of Republicans attributed their status principally to a "lack of effort," while 32 percent said poverty resulted from "circumstances beyond his or her control." Again, the numbers were reversed for Democrats and independents: Democrats picked the "circumstances" explanation by better than 2-to-1; independents did so by a margin of about 5-to-3.

And on two specific proposals now dividing Republicans and Democrats in Congress, raising the minimum wage to $10.10 an hour and extending unemployment benefits, the public, including many rank-and-file Republicans, sided overwhelmingly against the GOP: 73 percent favored the minimum-wage hike; 63 percent favored a one-year extension of unemployment benefits.

For Obama, now is not the time for defensiveness. His current difficulties owe less to Obamacare's early problems than to a broader alienation fostered by the Republicans' ability to block government efforts to ease widespread economic stress. 

The president should certainly play for some immediate policy victories, notably on immigration reform. But his larger task is the one Ronald Reagan always kept in mind: to encourage a shift in public opinion that is already moving toward his ideas.

Obama will be judged, of course, by the state of the nation when he leaves office in January 2017. But his place in history will depend on what is happening in 2027 and beyond.

E.J. Dionne's email address is ejdionne@washpost.com. Twitter: @EJDionne.