The recent polarization of American politics has been far more obvious on the right than the left. The emergence of the tea party movement and its influence in Congress has brought to the fore political values that are more conservative than those of the average voter.
But polarization is not a one-way street. While Republicans have become more conservative, Democrats have grown more liberal. The Pew Research Center's values surveys, spanning 1987 to 2012, show that Democrats as a whole have moved to the left in recent years. They are much more socially liberal than they were even a decade ago, more supportive of an activist government, more in favor of increased regulation of business.
While the move leftward has occurred among moderate and conservative Democrats as well as liberal ones, liberals have either moved further left or hold more intense views than moderates and conservatives.
And that's where comparisons with polarization on the right begin to break down. Although liberal Democrats have swelled in number, the advantage within the party still rests with moderates and conservatives. In Pew's nationwide survey in January, only 34 percent of Democrats called themselves liberal, compared with 63 percent identifying as moderate or conservative. In contrast, conservatives are a clear majority (67 percent) in the GOP, while self-described moderate and liberal Republicans make up just 32 percent of the party.
This might ensure that, despite the leftward trend, Democrats will not become identified as an extremist party like the GOP. By 54 percent to 35 percent, a January Pew Research poll found that the public continues to see the GOP rather than the Democrats as the party that takes more extreme positions.
Yet the gap within the Democratic Party is real — and it is not just ideological but demographic as well. Women and white voters make up a disproportionate share of liberals; liberal Democrats are also more affluent and better educated than the party as a whole. In contrast, moderate and conservative Democrats are more often male, poorer, less educated, and African American or Latino.
While Democrats share many core values, there are a number of ways that liberals differ sharply from the rest of the party and the rest of the country. According to Pew Research surveys:
36 percent of liberal Democrats think most people can get ahead if they work hard
39 percent think reducing the budget deficit is a top national priority
44 percent say they have old-fashioned values about family and marriage
62 percent think the government can do a lot to reduce poverty
54 percent think it's acceptable if another country is as powerful as the United States
Liberals also rate Hillary Clinton higher than moderate Democrats do, though they were largely not on her side during her 2008 presidential bid, once Barack Obama entered the picture. In that regard, it is instructive to note how quickly liberals have flocked to Sen. Elizabeth Warren: Fifty-four percent of liberal Democrats hold a favorable opinion of the senator from Massachusetts, compared with just 35 percent of moderate and conservative Democrats, many of whom don't know much about the high-profile progressive.
How much sway will liberal Democrats hold in the party, especially as the 2016 election approaches? Although they are a minority of Democrats nationwide, liberals are more politicized and make up a disproportionate share of primary electorates. For example, in 2008 they made up 56 percent of New Hampshire Democratic primary voters and 54 percent of Iowa caucus-goers.
In the shutdown era, Democrats have had a more moderate image nationwide than the tea-party-burdened GOP. But that image may be at risk if liberal Democrats set the pace for the party. We could see them rally around a progressive leader — Warren, New York Mayor Bill de Blasio or some yet-to-emerge candidate — who speaks their language of economic populism. If the agenda of this new New Left drives Democrats' choices, it might weaken the ideological and demographic coalition that has led the party to victory in four of the past six national elections.
Kohut is a former president of the Pew Research Center.