With now less than 100 days before the midterm election, it may be worth looking into whether or not the Democratic Party has a chance at flipping Congress.
First, a quick look at the Senate. RealClearPolitics begins with saying that 36 Democratic seats and 46 Republican seats are either not up for reelection, or are too safe to bother looking into. When you add the seats they name as "likely" Democrats come out of the midterms with 42 seats, and Republicans with 47, leaving 3 Democrats seats which "lean" Democratic, and Senator Ted Cruz's seat, which leans Republican, but there is reason to suspect a chance of the Texas seat turning blue. After that, there are the remaining 7 seats which RCP labels as "toss-ups." Of the seats, 4 are currently Democratic, and 3 are Republican. Currently, the split in the Senate is 51 Republicans, to 49 Democrats, so Republicans are hoping to widen their majority, whereas Democrats are hoping to at least gain a majority, which would mean flipping at least 2 seats. Most vulnerable are the 3 Republican "toss-up" seats of Arizona, Nevada, and Tennessee. Perhaps of the three, the most vulnerable looking is Tennessee, but overall the Senate looks to be fair game for either party, and the fact that Democrats have so many seats up this year does not bode well for them.
The House is a different matter. Democrats need 23 seats to gain control, and as was pointed out in this CNN article, the Ohio race was a close call, and "there are 68 Republican-held House districts that are more favorable for Democrats" - as in there are 68 Republican-held seats which Democrats are more likely to win then they were to win the Ohio seat, and the Ohio seat was held on by Republicans by the skin of their teeth. If you want more numbers to look at, FiveThirtyEight shows that Democrats odds of winning the house are 47.4% to Republicans 41.2%.
That being said though, it is surprising to see how the far left is doing. One might expect that with all of the support for Democrats, the whole country would be looking more left in general, but this is only true to a point. Although in the past I have made the argument that the Democratic Party should move more left, this issue gets more complicated depending on where you are geographically. The win by Ocasio-Cortez was a surprise, but her win doesn't seem to be the beginning of a new Democratic-Socialist wave washing over the US. This phenomenon was perhaps summed up best by Bill Shcher in this Politico article when he said "The Democratic Party is more liberal than it was 15 years ago, and there's no question that shift is partly due to an increasingly vocal, confident, confrontational democratic socialist faction. But it is still only a faction. Most Democratic nominees in competitive House races—not to mention incumbent Senate Democrats fighting for their political lives in red states—are not embracing single-payer or calling for the abolishment of ICE. They are mostly calling for improvements of the Affordable Care Act and a pathway to citizenship for the undocumented."
For Democratic supporters, it looks like there is a lot to be optimistic about (although there are some pessimists with some valid concerns). In the end, a midterm year, which are traditionally beneficial to the minority party, and a hugely unpopular president could spell a victory for the Democrats like we haven't seen, at least in the house. The real question is can the Democrats keep this momentum going throughout the following 2 years, or will it fizzle out? And if we do see a Democratic majority, in either, or both houses, especially with President Trump, what will the Democrats hope to do?
The one obvious answer would be to continue and embolden the investigation in Trump's dealings with Russia. And at the end of all of this, even if their momentum does wane, that is why a Blue Wave would be important, to see that Trump is held in check, and held accountable.