Democrats rebuilt their 'blue wall' in Michigan, Pennsylvania and Wisconsin. It's a big deal for 2020.

(CNN)President Donald Trump demolished the "blue wall" in the Great Lakes region two years ago. On Tuesday night, Democrats rebuilt it.

The party's candidates won races for governor and the Senate in the three states that delivered Trump the presidency -- Michigan, Pennsylvania and Wisconsin. Democrats padded their new House majority in the suburbs of Philadelphia and Detroit, while Milwaukee delivered the surge they needed to finally, on their fourth try, beat Republican Gov. Scott Walker.
The Democratic victories set the stage for a 2020 battle royale in the three states that could decide the presidency.
They could also shape a Democratic nominating contest set to begin almost immediately, underscoring which states Democrats are best poised to win and which candidates and issues most appeal in those states.