While The Plum Line reports:

In another sign that House Dem leaders are eager to silence talk about them losing the House, top Democrats are circulating a memo on Capitol Hill that lays out a detailed case for why Republicans will come up short this fall.

Daniel Foster puts it slightly differently:

[Y]ou’re seeing the DCCC telling their members that the House majority is going to a beautiful farm upstate where it can run freely and play with other Democratic majorities.