Since yesterday the Clinton-Trump spread has jumped to 6.3%, a good jump based on new polls. We're still seeing a Clinton convention bounce but a bigger bounce may mean she'll retain some of it. The McClatchy/Marist poll that has Hillary Clinton up 14% appears to be an outlier. It's worth noting that the three likely voter polls have Clinton up by 4.3%, while the six polls of registered voters have her up by 7.3%. People who don't vote tend to like Democrats more, but if they don't vote their preference doesn't count. Donald Trump may well lose by 10-15% in the general election, as some predict, but the polls right now don't suggest that.
That McClatchy/Marist poll also has Democrats up by 8% in generic congressional ballot. The survey is registered, not likely, voters, and it is an outlier in the Presidential ballot. Would 8% be enough for Democrats to take the House?
In 2012 Republicans won the 218th district by 6.1% and lost the popular vote by 1.2%. So Democrats would’ve roughly needed to win by 7.4% to win it then. The PVI of the 218th district is only R+2.8%, however. Because Republican House candidates tend to be stronger than their Presidential nominee, especially this year, winning by 2.9% isn’t likely to get Democrats the House. I'm skeptical the generic ballot is more than D+4-5 right now after the Democratic convention bounce.
If the election were held today I'd give Democrats a 25% chance to take the House.
The election isn't today.