Twitter is not the real world. If you’ve spent any time on Twitter arguing about politics then you probably already know this. But a new survey by Pew Research has confirmed that Democrats on Twitter are both further to the left and less interested in finding middle-ground with Republicans than Democrats who don’t use the platform.

A 56% majority of Democrats and Democratic-leaning independents who use Twitter describe their political views as liberal or very liberal. This share is substantially larger than the 41% of non-Twitter Democrats who describe themselves in this way.

Differences between Democrats on and off Twitter extend beyond ideology. About two-thirds of Democrats who do not use Twitter (65%) say it is more important for a Democratic candidate to seek common ground with Republicans, even if it means giving up some things Democrats want. A smaller share of Twitter-using Democrats (54%) take this view; 45% prefer a candidate who will push hard for policies Democrats want, even if it makes it much harder to get some things done.

Naturally, this divide winds up shaping who Democrats support, with Twitter progressives being far more likely to support Sanders or Warren:

Democrats on Twitter are 11 points less likely to name Joe Biden as their first choice for the nomination than Democrats who are not on Twitter. By contrast, candidates such as Elizabeth Warren (+8) and Bernie Sanders (+7) receive higher levels of support among Twitter-using Democrats than among those who are not Twitter users. For Biden and Warren, differences in support between Twitter users and non-users hold even after accounting for factors such as age, education and political ideology.

Here’s a chart put together by Pew to show the on vs. off Twitter comparison for leading candidates:

As you can see, Bernie Sanders is getting overwhelming support on Twitter, especially from Dems who are not register to vote (bottom row). Meanwhile, Biden has a strong advantage over Sanders among Dems who are a) not on Twitter and b) registered to vote (middle row). The important point is that there are more Dems who are not on Twitter as those who are.

Last month the Atlantic pointed to this same divide and proclaimed Twitter a progressive bubble, a place where Jeremy Corbyn was expected to win the UK election and where, even after his resounding loss, many on the left found it hard to accept. The potential impact of this echo chamber on American politics seem obvious. As Jonathan Chait has argued, a group of progressives on Twitter believe Bernie Sanders can win a general election by running hard left on every issue. That’s true even though some moderate Democrats are warning that Sanders is setting the party up for disaster this November.

But recent polls have shown Sanders is surging in the real world. We’ll have to wait just over a week to see if the results in Iowa and New Hampshire show as much strength for Sanders as his support online would suggest.