Taxing the rich. For two decades, Democrats have been largely united on taxes. Bill Clinton raised the top marginal tax rate (which now applies to couples making more than $450,000) to 39.6 percent. Mr. Obama spent years fighting — and ultimately succeeding — to raise it back to that level, from a 35 percent rate.

But now the issue gets trickier for Democrats.

Total federal taxes on top earners are already near the top of their narrow range over the last 35 years. But pretax inequality has soared during that time. And federal tax rates are still much lower than they were in the 1950s, ’60s and ’70s.

Have the politics of inequality changed to the point that Mrs. Clinton will propose a top marginal rate above 40 percent? Or will she instead propose more subtle tax increases, such as reducing tax breaks, as Mr. Obama recently has?

Either way, she seems likely to push for middle- and low-income tax cuts. As a result, she will need either to propose further tax increases on high earners — or to acknowledge that her plan would increase the budget deficit.

Bargaining power. Top Democrats spent much of the 1990s moving to the right on economics. They have spent the last decade inching back to the left. The move isn’t really about the personal views of Mr. Obama and the Clintons. Instead, it’s a reaction to the great wage slowdown of the last 15 years, which has left the party looking for more aggressive ways to address inequality.

Take the party’s stance toward labor unions. Democrats who previously were wary of aligning too closely with unions are now searching for ways to strengthen workers’ bargaining power. The Commission on Inclusive Prosperity, a group with close ties to Mrs. Clinton, recently made “expanding worker voice” one of its centerpiece recommendations. “If you made it less easy for employers to fire union organizers, you would meaningfully impact the amount of collective bargaining,” Lawrence Summers, the former Treasury secretary, said.

Although labor leaders support many of Mr. Obama’s decisions, they also hope that the next Democratic nominee will go further — on enacting overtime-pay rules, on using the bully pulpit to criticize corporations and on appointing labor-friendly advisers. “We have learned through bitter experience that it really matters who makes up a president’s economic team,” said Damon Silvers, a top A.F.L.-C.I.O. official.