Two topics have dominated the political dialogue this week: Bedbugs (who has them — or doesn't — and who reacted poorly to being described as one) and one poll (Monmouth), which showed Biden's lead in the race for the Democratic nomination slipping. Needless to say, I'm not particularly interested in diving into either one of these. But the outcry over one national poll (that even Monmouth pollsters ultimately conceded was an outlier), provided an opportunity to take a broader look at the most recent national polls. I wanted to focus less on the horserace and more on the demographics. Where are certain candidates strong and where are they weak.

To do this, I dug into the crosstabs of six of the most recent, reputable national polls. I also included the share of the vote that each group represented at the national level. For example, according to Ron Brownstein's excellent analysis of the 2016 CNN exit polls, 62 percent of the Democratic electorate was white, and 24 percent was black, voters older than 45 made up 60 percent of the overall electorate, while those under 45 years old constituted 40 percent.

Obviously, there is no national primary, so the make-up of the electorate nationally can look very different from that of an individual state. For example, we know that in states like Iowa and New Hampshire, white voters are over 90 percent of the electorate, while in South Carolina, it's more like 35 percent. Nationally, 32 percent of Democrats called themselves "moderate or conservative," but in South Carolina, almost half (46 percent) of Democratic voters described themselves that way. But, understanding where individual candidates stand among key demographic groups is critical in understanding the battle for the Democratic nomination.

Here Are My Biggest Takeaways:

The Coalitions Are Clear, But How Stable Are They?

In looking across the six polls, some clear patterns emerge (as does the Monmouth poll's outlier status). Biden is strongest among older, African-American, and moderate/conservative Democratic primary voters. Sanders is strongest among younger voters, while Warren is strongest among the most liberal voters and those with a college degree. That's not a new discovery, of course. What was striking, however, is how consistent these coalitions were among all the different polls — regardless of what the head-to-head poll numbers showed (well, except for Monmouth).

What also stuck out to me was the size of the lead candidates held in certain demographic groups. For example, while Sanders does best among younger voters, he doesn't rack up the large margins with these voters that Biden does among older voters. Scroll along the age breakouts in the chart and you see Biden with double-digit leads among voters over 45-years-old. Meanwhile, Sanders' lead among 18-34-year-olds is in the single digits. In the Quinnipiac poll, for example, Sanders takes 31 percent to Warren's 25 percent, and Biden pulls up with just 10 percent. But, among those over the age of 65, Biden has an almost 30 point lead over his closest competitor (Warren), while Sanders sits at just 4 percent.

Why does Biden's solid lead with older voters matter? Because older voters (those over the age of 45), make up 60 percent of the overall Democratic electorate. And, it's not just nationally. Older voters made up anywhere from 59 to 65 percent of the electorate in the first four voting states — Iowa, New Hampshire, Nevada and South Carolina. Furthermore, Brownstein found, that "[s]ome private analysis conducted for Democrats eyeing 2020 has found the potential electorate tilting even more heavily toward older voters." In other words, the fact that Biden has — so far — consolidated older voters, while younger voters are divided between Warren and Sanders — gives Biden a big electoral advantage.

In polls where voters were asked to describe their ideology, Warren is way ahead of her closest competitor (Sanders) among those who say they are "very liberal." The Pew poll shows her getting 35 percent of that vote to Sanders' 19 percent. But, among those who say they are liberal or somewhat liberal, voters are pretty evenly divided among the top three candidates. And, among those who say they are moderate to conservative, Biden has double-digit leads in all but the Monmouth poll. Again, looking to Brownstein's analysis of the 2016 exit polls, almost 40 percent of the electorate called themselves moderate or conservative, while just 25 percent said they were very liberal. As long as Biden holds big leads among moderates/conservatives, and holds his own among the 'somewhat' liberal, he can afford to lose the 'very liberal' vote to Warren.

In other words, as long as neither Warren nor Sanders can consolidate their leads among demographic groups in the way Biden has done with his, or if they can't start to narrow Biden's margins, it will be hard to upend him.

Chicken or Egg:

As we've been writing about for months (seems like years), Democratic primary voters are more interested in electability than we've seen in recent memory. The CNN poll found that 54 percent of Democrats preferred a candidate who had a strong chance to beat Trump, compared to 39 percent who preferred a nominee who shares their positions of major issues. A Fox poll found that, when given a choice between a nominee who will "restore the country and get back to normalcy" or one who would "fundamentally change the way things work" in DC, 60 percent chose "back to normalcy." That same poll found that Democrats were more evenly divided on the question of preferring a candidate who would "build on Obama's legacy" (48 percent) versus one who will "take a new and different approach" (47 percent). But, the same coalition that prefers a candidate that can beat Trump, return to normalcy and build on Obama's legacy is also the Biden coalition. Those that prefer more structural change and a candidate's policy positions to be closest to their own, look more like Sanders voters.

For example, the Democrats who were most interested in a candidate who could beat Trump versus a candidate who shares their values were older (over the age of 45) and identified as moderate to conservative. Those who were most interested in a candidate who shares their values were younger and did not have a college degree. Support for a candidate who would return things to normal versus a more transformational candidate was 33 points among those over age 45, but just 9 points among those under age 45. And, just 45 percent of those under the age of 45 wanted to vote for a candidate who would build on Obama's legacy, while just 43 percent of those over 45 years old wanted a candidate who would take a new and different approach than Obama.

In other words, is Biden winning over the people who want most to beat Trump, or are the people that most want to beat Trump the kinds of people that are also attracted to Biden?

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