The midterm is fast approaching. How many races are actually competitive? Which polls should you trust? And why is California so important this year? Here&rsquo;s what you need to know before the Nov. 6 election.Here&rsquo;s the main thing to keep in mind about the contest for control of the House this year: About 5 out of 6 seats in Congress really aren't in doubt. They&rsquo;re either heavily Democratic or heavily Republican, and they&rsquo;re not likely to flip.The battleground consists of roughly 60 to 70 districts nationwide, nearly all of which are in territory that Republicans have held for years &ndash; in some cases for decades. Democrats have to net at least 23 additional seats nationwide to get a majority. At least half a dozen seats in California are strongly competitive.