Congressional Quarterly is projecting that the GOP will hold the House and the Senate.  However, the projection for the House is based on the assumption that the GOP will win all seats currently listed as safe, favoured or Republican-leaning.  CQ explains the dangers for the GOP:

Just as worrisome for Republicans, they hardly have a lock on the 220 races now tilted in their favor. In 20 of them, the Republican has only a slight edge because of incumbency, fundraising advantages or political demographics. And so the Democrats could win any or all of them if their candidates’ strengths gain a bit of traction — or if the voters’ mood shifts much more against the GOP, or against incumbents in general.

Only 10 seats now held by Democrats, by contrast, are that closely competitive.

Beyond these races that are tossups or “leaning” to one party or the other is a third category: contests in which the front-running candidate has serious advantages that make election likely, but where other factors make an upset plausible. And here is where the partisan imbalance is greatest of all: There are 25 seats where Republicans are favored — pretty solid, but not quite safe — but only eight seats where Democrats are similarly vulnerable to an upset.

It is always possible that the GOP will buck the “sixth-year” trend and lose relatively few seats, and the Dems may not be able to exploit their advantages in this election, but the fundamentals (approval of Congress, wrong-track numbers, signs of anti-incumbency cropping up all over the country) are pointing towards a repudiation of the GOP in November.  National Journal would not keep talking about an electoral “hurricane” if there were nothing to back it up. 

Naturally, the folks at NRJoe spin it in the best possible way, noting that if the election were held today the GOP would win.  But anti-incumbency tends to grow like a wave and will accelerate as campaign season begins and people begin to be reminded what they don’t like about the majority party.  Three months before last Tuesday no one had ever heard of Ned Lamont, much less expected him to win.  Three months is an aeon in politics.