America’s increasing diversity has propelled Democratic competitiveness. The presence of five women, two blacks, one Latino and a gay man in the field of candidates only begins to describe the changes that has introduced.

Sen. Kamala Harris of California endorsed the concept of reparations to compensate African-Americans for the historic injustice of slavery. Are reparations – shunned by President Barack Obama and other Democratic veterans taught by experience to fear white backlash – now politically sustainable?

Harris herself faces questions about the justice of her prior career as a prosecutor from younger Democrats disdainful of “mass incarceration.” Biden’s support for get-tough legislation in response to crime fears of the 1980s and 1990s represents an even greater potential liability because he is a white man.

Or does it?

A recent Monmouth University poll showed 56 percent of Democrats prefer a candidate who would run strongest against President Trump over one who shares their views on issues. Electability represents Biden’s central argument.

An NBC News/Wall Street Journal poll, however, found something different. In that survey, 56 percent of Democrats preferred the candidate whose views come closest to their own.

It also found that 55 percent want a candidate seeking larger, costlier changes over smaller steps easier to move through Congress. That augurs well for Warren, who backs a new wealth tax, a breakup of giant technology firms, and “Medicare for All,” or longshot Gov. Jay Inslee of Washington, who has centered his campaign around action to slow climate change.

Biden, 76 years old, and Sanders, 77, lead Democratic polls. But nobody knows whether their standing reflects a floor or a ceiling. In the NBC/WSJ poll, six in 10 Americans expressed unease about a candidate older than 75.

Worse for Sanders, seven in 10 balked at the idea of a socialist candidate. Yet the younger universe of self-described Democratic primary voters split evenly on that idea. Americans overall advocated more help from government, not less.