I'm happy to see some items like this one, pushing back on the notion that Democrats are destined to have big losses in two years:

Only three of the last seven two-term presidents who were in office for both midterms had a bad second midterm in both chambers — George W. Bush, Dwight Eisenhower and Franklin Roosevelt. Woodrow Wilson and Ronald Reagan both lost control of the Senate in their second midterms but actually performed better in the House the second time around.

None of this is to say that Obama has a good chance at his party winning back the House for the final two years of his term in 2014. In fact, over the past century, only one president’s party has gained seats in the sixth year of his presidency — Clinton. (He only gained five seats in the House and the Senate stayed the same.) [...]

But the idea that there is something perilous about the sixth-year midterm, as opposed to the second-year midterm, isn’t really borne out by the numbers — particularly in the House. And if anything, the fact that Obama sustained huge losses in 2010 suggests his worst midterm is behind him, and the itch has been sufficiently scratched.

This is one of those anecdotal stories that bugs me. If you look at all the two-term presidents we've had since FDR (this won't take long, because not many actually served two full terms) and try to explain the "six-year itch" for each of them, here's what you get:

• Bill Clinton: didn't have one. Democrats did well in 1998 and Clinton would have won another term if possible.
• G.W. Bush: had a disastrous itch thanks to Iraq and other factors, like corruption/scandal.
• Ronald Reagan: had a bad one, due to Iran-Contra and a general sense he wasn't really up to the job anymore. Also, while the economy was recovering, it was still particularly awful in rural areas. Which is how we got Tom Daschle, among others.
• Dwight Eisenhower: another diastrous sixth year, but this was due to a recession also, particularly in rural areas.
• Harry Truman: pretty bad sixth year, due to Cold War setbacks, corruption/scandal and limpid economy.
• FDR: suffered bad losses in his sixth year due to his meddling with the Supreme Court and a noble but doomed effort to make the Democratic Party less racist , won a third term in 1940 anyway.

The thing about the "six-year itch" is that it assumes all of these are somehow connected, that there's some sort of inevitable trend to them. But as Blake argues, there isn't one, and plenty of presidents (*coughcough Carter) exhausted their goodwill within four years. Others, like Roosevelt, Clinton and arguably Reagan, were still in good enough shape to run again. There's nothing magical about the number six. This list doesn't have a coherent theme running through it, other than that if you're a Republican and you preside over a rural recession, you're in for a pretty rough time at the ballot box. In some cases, the president's party lost because of military mistakes. Other times, like FDR and Woodrow Wilson, bad political decisions are to blame. Or it could be economics. Or, perhaps something that hasn't come up yet. Or nothing! This is such a small dataset that any grand theory extracted from it is going to be crude, and would have to have outliers. In scientific terms, this is a non-publishable finding.

This is how I see it: Barack Obama seems to run a pretty tight ship in his White House, so serious scandals are less likely, though obviously always possible. The economy is visibly starting to recover, which could obviously stop any time, but we're starting to get into the time period after a financial crisis where even the most stubborn economies start to bounce back (cf. Reinhart-Rogoff). Obama intends to scale back Afghanistan operations in 2014. I don't expect big gains in 2014, because the rare times the presidential party has done that in a midterm (like 1934 and 2002) clearly had more to do with frazzled, dumbfounded opposition than with the strength of the president's popularity, but I hardly see the makings of a rout there. Midterms are usually about voters letting off steam, how bad the circumstances are usually predict how much is let off. Holding all else equal, if trends continue 2014 should probably see some nominal Senate losses for Democrats as well as single-digit House gains, as Democrats are pretty close to their floor in that chamber and there are more vulnerable Republicans than Democrats remaining there. The one area where we could see significant turnaround is for governors: most of the 2010 class of "Red Squad" governors are quite unpopular, today's batch includes John Kasich and Nikki Haley, remarkably. Rick Snyder is also busy immolating himself politically. The sheer number of Tea Party governors who face significant obstacles to another term is staggering, and it includes Rick Perry, Rick Scott, Tom Corbett of PA, Paul LePage of Maine, and possibly Nathan Deal of Georgia. Add in the steep climb Ken Cuccinelli is going to face to hold onto the Virginia statehouse, and it's very plausible that a lot of prominent GOP talent will be wiped out in 2014. Though obviously much depends on the quality of opposing candidates, perceptions of the economy, primary challenges, etc.