When Scott Walker announced his candidacy last week, he joined one of the most crowded and diverse presidential fields in modern history. This has its carnival aspects — as with the furor over Donald Trump's provocative statements on immigration and crime, among other things. Trump's rise in some polls and the large audience he drew in Phoenix recently have alarmed Republicans and conservatives, while delighting Democrats and liberals.

But even Trump's remarks have resonated for a reason. They are rooted in the Republican Party's current struggle to adjust to sweeping changes in the national identity — or identities.

These changes may be the most important legacy of Barack Obama's presidency. They began with his election in 2008 and climaxed with the recent Supreme Court rulings on same-sex marriage, health care and fair housing, not to mention the campaign to remove Confederate flags from statehouses in the South.

While a majority of the country seems to welcome these changes, a great many Americans do not. And they are demanding their say. This puts Republican presidential hopefuls in a bind as they seek to appeal to social conservatives, who will have outsize influence in early primaries and caucuses, and then later try to attract moderates and independents in the general- election campaign.

This isn't a new problem for Republican candidates. They have stumbled against it repeatedly in recent presidential elections. What does seem different this time are the more diligent efforts some are making to soften the edges of conflict by emphasizing their personal history or journey rather than their ideological or policy views.

Thus the fixation on "relatability," the buzzword of this election cycle. The term is relatively new in politics. As recently as 2012, political observers usually spoke of a candidate's ability (or failure) to connect with voters or "sell" his or her message. The distinction between connecting and "relating" is not merely semantic. To "connect" is in some way to impose your will on someone else. "Relatability" reverses the power current. It subordinates the politician's identity and values to the voters'.

As a result, candidates now tend to play down their accomplishments and records, and instead highlight their likable, ordinary Everyman or Woman selves.

Consider South Carolina Sen. Lindsey Graham, a leading Senate foreign policy voice and occasional bipartisan compromiser. When he announced his candidacy last month, he staged it within view of the bar and poolroom his mother and father once owned in Center, South Carolina.

"I lost my parents, and had to struggle financially and emotionally," Graham said. "There are a lot of so-called 'self- made' people in this world. I'm not one of them. My family, friends, neighbors and my faith picked me up when I was down, believed in me when I had doubts. You made me the man I am today."

The words were moving, but oddly generic. They could apply to almost any success story, rather than to the specific case of Graham, and the record he has compiled in 21 years in Congress (four terms in the House, a third term now in the Senate), and his previous career as an Air Force lawyer and then a staff judge advocate, qualifications he skimmed over in his remarks.

Other candidates also seem to be straining for the common touch. In his announcement, Walker touted his first jobs, washing dishes "and flipping hamburgers," while his sons have made fun of his corny taste in summer apparel ("jean shorts and white ankle socks"). Carly Fiorina, the former chief executive officer of Hewlett-Packard, regales audiences with her struggles as a fish out of water in law school. Chris Christie's recent announcement of his candidacy was at the high school he attended in Livingston, N.J. The candidate "was introduced by old friends, not political allies," National Review reported, adding:

"His high school friends were evidently in attendance. At one point Christie, in a tangential aside, explained that what had sounded like boos during an introduction were actually people yelling 'Juice,' because that was the speaker's nickname in high school."

It isn't just Republicans who have been bitten by the personal-history bug. Hillary Clinton's poll numbers and matchless name recognition might suggest she has a clear path to the nomination and a possibly historic run to the White House. Yet she too is said to be preoccupied with "relatability." Her campaign website notes that "she attended public schools and was a Brownie and a Girl Scout" and "played in a girls' softball league." These homely data points seem intended not so much to round out as to offset her exceptional career in public life.

The search for relatability can be embarrassing. It comes close to pandering — the sin that dogs almost every politician at one time or another. But this criticism should be measured against the challenge of appealing to large numbers of people at a moment when the differences among them are so great — and when even the most fundamental values seem in flux.

It may also seem that the ideal of the politician as grand statesman who floats above conflict and heals divisions is fast becoming an anachronism. Actually, its demise began long ago.

The most artfully shaped personal history in American political literature was the campaign biography of Franklin Pierce, published in 1852. Its author was Pierce's longtime friend, Nathaniel Hawthorne, the period's most distinguished American writer. In his telling, Pierce embodied the highest political virtues, beginning with his lifelong apprenticeship in politics and his deference to his forebears and elders.

As a member of the House, Pierce modeled his speeches on "the brief but pregnant arguments and expositions of the sages of the Continental Congress," Hawthorne wrote. In the Senate, Pierce acknowledged the pre-eminence of "gigantic figures" like John C. Calhoun, Henry Clay and Daniel Webster.

It is hard to imagine the ambitious young senators of our time showing the same "exquisite sense of propriety" that Hawthorne praised in Pierce. Certainly Obama did not. According to most accounts, he loathed the Senate, which he mockingly likened to the poky Illinois State Legislature. "It's basically the same as Springfield," he is quoted as saying in "Game Change," John Heilemann's and Mark Halperin's book on the 2008 election, "except the average age in Springfield is forty-two and in Washington it's sixty-two."

The Republican field of 2016 includes three first-term senators who share Obama's disdain. Ted Cruz and Rand Paul have openly clashed with and undermined senior Republicans, and Marco Rubio is reportedly fed up with the Senate's sluggish pace. "He's frustrated with the fact that the Senate doesn't do anything," one of his supporters, the Miami billionaire Norman Braman, has said.

This might seem disrespectful or narcissistic. But politics has become a showcase for individual candidates, who speak to and for particular constituencies, rather than for clubhouse loyalists. As it happened, Franklin Pierce's deference was a liability. Bowing to Democratic Party dictates, he signed the Kansas-Nebraska Act, which permitted the spread of slavery to the territories and revitalized the "free soil" movement, giving rise to the Republican Party.

It was a leader in that new party, Abraham Lincoln, shrewder and more self-contained and firm in his commitment to containing slavery, who led the country through its greatest crisis.

At first Lincoln too distrusted the politics of "relatability." He brushed off a would-be biographer, saying, "There is nothing in my early history that would interest you or anybody else." That changed quickly. Eyeing voters in the Western states, he talked about "his poor schooling, years of poverty, and manual labor," Doris Kearns Goodwin notes in "Team of Rivals." At the party's national convention, "Republicans paraded through the streets carrying the rails Lincoln had supposedly split." And he joined in, showing an interviewer the souvenir rail he had been sent by someone he had worked for when he was 14.

Today we would call Lincoln's rail-splitter image his personal "brand." But it symbolized something bigger than himself — a shift in the country's power away from the Eastern states and toward the hinterland. His "aura of the Western man, the man of the prairie," in Goodwin's phrases, made him the agent of what another Lincoln scholar, Garry Wills, has said is the best aspect of American history, the "slow but persistent spread of egalitarianism."

The shift in our own time may be just as profound. It involves geography and race, just as it did in Lincoln's time, but includes other changes as well. America today is not so much divided as atomized, along the lines of what until recently was called, often disparagingly, "identity politics." That is just another way of saying we have become a nation of ever more distinct groups, whether gays and transgender people who insist on full rights, or Christians rallying to the call for "religious liberty," to cite only two examples most recently in the news.

This tangle of competing interests explains the glut of Republican candidates. Which of them will be able to reassure the different factions — or at least cobble together enough of them to build a winning coalition? It is too early to say, but the competition will begin in the stories the candidates tell, about themselves and the nation.

Sam Tanenhaus, author of "The Death of Conservatism" and "Whittaker Chambers," is working on a biography of William F. Buckley Jr. He wrote this article for Bloomberg View.