Because, as ABC shows, that's not true right now.
If a majority of Millennials right now want a GOP Congress, then Democrats, starting with the President and moving down, are doing at least one something wrong politically. (By politically, I'm talking about the art of winning at politics, not the skill of governance, though they may be doing stuff wrong there, too.)
And, yes, I know that Millennials (well, youth in general in political history in the US) have lower voting turnouts than the national average. So, note what I’ve emphasized in this pull quote:
Millennials who said they will “definitely be voting” favor a Republican-led Congress 51-47 percent, according to the poll. An ABC News/Washington Post poll released earlier this week found that roughly half of Americans plan to vote for Republicans this election, 50-44 percent.
Those aren't good numbers. Now, part of the "definitely be voting" reflects that active voters, even among younger cohorts, tilt GOP in midterm elections. But, that itself is a problem. If the vaunted Obama machine — and its offshoots like Battleground Texas — can't get Millennials more interested in midterm elections, it's not quite so vaunted, is it?
Per the "of color" part, the story notes that just 46 percent of Hispanic Millennials favor Obama. So, it's not just Congressional Democrats.
That said, there is this sidebar.
It's not just Millennials that don't like Congressional Democrats a lot, and it's not just Congressional Republicans that aren't liked a lot. Disapproval of Congressional Democrats is at a record. Again, some folks with a D after their name aren't doing the right things politically.
Whether that's relaying the D message, or the anti-R message, with a harder mailed fist, or, if a mailed fist is in play, either wrapping it in a velvet glove or topping it with brass knuckles, or what, I don't know.
Again, though, depending on anti-Republicanism as a demographic ain't gonna cut it.