Following in the footsteps of Washington Gov. Jay Inslee, who earlier this week ended his 2020 presidential campaign, Rep. Seth Moulton, of Massachusetts’ 6th District, has decided to take the same course. Moulton had made absolutely no progress in building a coalition of voters nor has he been able to move the needle in terms of polls and fundraising, and he never made it onto the debate stage.

There’s hardly a reason to report on his decision to end his campaign given the insignificance of his impact on the race. However, it’s the analysis Moulton gave on his way out the door that is worth noting and discussing further, per the New York Times:

Mr. Moulton suggested that most of the other Democratic candidates were also laboring in vain at this point, with only a tiny few — Mr. Biden and Senators Elizabeth Warren and Bernie Sanders — remaining as real competitors for the nomination. He warned in the interview that if Democrats were to embrace an overly liberal platform, it could make it harder for the party to defeat President Trump.

“I think it’s evident that this is now a three-way race between Biden, Warren and Sanders, and really it’s a debate about how far left the party should go,” Mr. Moulton said.

Among the sprawling Democratic primary field, Moulton was one of the less progressive candidates on stage. He did not choose to endorse another candidate, though he seems inclined toward the candidacy of former vice president Joe Biden.

However, is Moulton’s assessment of the race accurate? Is it down to a three-person race between Biden, Sanders, and Warren? Being this far out it’s hard to rule out an upswing in some of the mid-tier candidates like Kamala Harris or Pete Buttigieg, but the race does seem to be crystallizing more so in recent weeks.

Looking at the RealClearPolitics polling average, Biden, Sanders, and Warren are the only candidates in double-digits while the rest of the field seems to be losing support. If there is a trend to be noticed, it’s that the divide between the upper tier and lower tier of candidates is becoming increasingly more evident.

RCP Dem Polls August

Into July, Sen. Kamala Harris was still easily in the mix of “top tier” candidates, though her star power began fading quickly into late July, and then entirely bottomed-out following the debate at the end of the month. Her candidacy lost support and it looks like Warren has been a big recipient of some of Harris’ voters.

Over 60% of the Democratic primary voter share is now held between the top three candidates which means that Moulton’s view of the race, for the time being, is a reasonable conclusion. In his view, the primary is boiling down to the choice between Biden, a more “mainstream” establishment Democrat, and the sharp contrast of Bernie Sanders or Elizabeth Warren. Bernie has seen his numbers erode somewhat while Warren has been improving.

The September debate is probably key to the continuation of this decision within the party. This dynamic will be even more evident if the debate stage stays set at 10 candidates and there is only one night of debating on September 12. That would mark the first occasion where Biden, Sanders, and Warren will share the same stage on the same night.

If Moulton is correct, and the race is down to just three serious, formidable candidates, expect to see more candidates calling it quits as we finish up the Labor Day holiday in early September.