Democrats have to win close to 70% of the popular vote to get majorities in the WI state congress. It's just that lopsidedly gerrymandered.
That is why the gubernatorial elections are so important. This is going to have to be a multi-cycle effort, and fortunately for Democrats, 2018 leaves Republicans over-extended in Govs offices, with many term-limited. 2020 hopefully will give them an opportunity to build on that in a more limited number of states, such as Indiana, Missouri, etc.
If Democrats do well, they can have a much less painful round of redistricting in 2021-2022.
Yeah. Those gubernatorial races in places like Florida, PA, Michigan, Ohio, Illinois, Maryland, Minnesota, Wisconsin, and Virginia will go a long way towards making the chambers and congressional maps much more competitive.
Chambers that Dems should target for takeover prior to redistricting are:
VA Senate (this should be the easiest)
CO Senate
VA House (if they gained about ten seats or so this year it puts them in position for 2019)
FL Senate (Probably heaviest lift on this list. Would probably take good D years in 2018 and 2020)
MI House
MN Senate
NY Senate
NH House
NH Senate
ME Senate
CT Senate
AZ Senate
MN House
Surely Maine and New Hampshire are pretty low priority from a redistricting perspective since they only have 2 CDs each and thus little room for gerrymandering?
AZ Senate doesn't matter for redistricting either do to the non-partisan commission.