The charts above are made from information provided by the website of RealClearPolitics. It shows the latest polls taken (in the last month and a half or so) of the approval ratings of both Congress and the president. The most significant figures are those on the far right -- which is an average of all the polls (and in the 2012 election, this RCP average proved to be closer to the outcome than any individual poll).
For a while now, I have been disagreeing with the GOP pundits who say that the coming election is going to be a referendum on President Obama. And I believe these numbers back up my view. While the president's numbers are not as high as he (and Democrats) would like them to be, they are astronomical when compared to the congressional numbers.
Only the teabaggers think they'll be voting against the president (and Democrats wouldn't have those votes no matter how popular the president was). The rest of America knows this is not a presidential election -- and they are going to vote on their unhappiness with this Congress. The voters have been angry at Congress for a while now, and it doesn't look like their attitude is going to improve before the election. The only real question, since the Republicans have a majority in the House, is whether the anti-incumbent mood of the voters is going to result in the flipping of control of the House (and the last two elections where voters were nearly this unhappy did result in that happening).
The chart below shows the current voter feelings when asked about their feelings on a generic party ballot. It shows the Democrats with a slight lead (but a lead within the margin of error of most polls). That also verifies something else I have been saying -- that this election hinges on turnout. A large turnout will favor Democrats, and a small turnout will favor Republicans. I still think the House can be flipped, but only if the Democrats are able to turn out a large percentage of voters.