President-elect Joe Biden will take office vowing to bridge partisan differences and unite Americans. It will not be easy. 

Biden will have to work with a Congress that is deeply divided, reflecting divisions among the American people that have grown stronger and more intense. 

Beginning in the 1990s, we entered a period of protracted polarization. Political groups became more active, more aggressive in their public dialogue, and more insistent in their policy preferences. Republicans are more consistently conservative; Democrats are more consistently liberal. Republicans accuse Democrats of being socialists and unpatriotic. Democrats accuse Republicans of being bigoted and chauvinistic. 

Increasingly, each side tends to be suspicious of the other. They view their political adversaries as not just wrong, but as a threat to democracy or national security. They have sharply opposing views on the economy, climate change, racial justice, law enforcement, and even whether the COVID-19 pandemic is real and serious. 

Sometimes I think that Democrats and Republicans live in different worlds. They gravitate toward separate houses of worship, schools, neighborhoods, bars and restaurants, and vacation destinations. They consume different news media and watch different movies and television shows. They even purchase different food at the supermarket. They are less likely to have friends from the opposite party. I run across Democrats who do not want their children to marry a Republican, and vice versa. 

Republicans are more likely to live in rural areas than Democrats. We find that Democrats are geographically more mobile and more likely to live in cities and suburbs. Republicans embrace traditional values and tend to identify their political views with Christianity. Democrats are often more socially liberal and less tied to traditional social values and religion. 

These trends were noticeable during the presidency of Barack Obama, when the country seemed to move left on issues like abortion, same-sex marriage, and addressing inequality. Donald Trump’s election reflected a reaction: Republicans became more conservative in some ways but also more willing to use government power to implement their policy preferences — a change from the past. 

All of this, of course, makes the life of a politician challenging. The greater the polarization, the tougher it is to build consensus to solve problems. 

However, the public clearly wants politicians to work together, to move beyond polarization, to cooperate and get things done. Surveys find that most voters want government to address the needs of all Americans, not just people like themselves. When officials say they are taking a bipartisan approach, the claim typically meets with approval.

Biden campaigned with a promise to “restore the soul of America.” He identifies himself as a moderate and seeks to govern from what he defines as the political center. For the most part, his cabinet choices tend to represent the moderate strain of the Democratic Party. 

He has spent a lifetime in government, and he believes he can work across the aisle and advance bipartisanship and cooperation. He has some advantages in following Trump, who did not try to win over public opinion but catered to his political base. 

Biden, of course, will not be able to do this on his own. He will need cooperation, from Republicans and from Democrats. Many people wish him well, but others will oppose his every move and try to defeat his program. That is the way it is in our politics, a system that presents its challenges, but over the years has served us reasonably well. 

The big challenge is, always, to make it all work.        

Lee Hamilton, 89, is a senior advisor for the Indiana University (IU) Center on Representative Government, distinguished scholar at IU Hamilton Lugar School of Global and International Studies, and professor of practice at the IU O’Neill School of Public and Environmental Affairs. Hamilton, a Democrat, was a member of the U.S. House of Representatives for 34 years (1965-1999), representing a district in south central Indiana.