We've written a lot in recent weeks about how the Senate map is looking better and better for Republicans. Recruiting, the mood of the electorate and a wave of outside spending from the Koch brothers-backed group Americans for Prosperity have combined to make for a landscape that looks riper and riper for a GOP takeover.

One way to look at the state of play is to compare it to a year ago. Thanks to Robert Blizzard at the Republican firm Public Opinion Strategies, we can do just that. The following chart details the movement between March 2013 and now in states with very to remotely competitive Democratic-held Senate seats. A year ago, 11 such seats were in the Cook Report's "Likely Democratic" or "Lean Democratic" categories and none were in the "Lean" or "Likely" GOP buckets. Now, three are in the latter and only five are in the former. And the number of "Tossup" races has increased by two.

Democrats' outlook in Arkansas, North Carolina, Louisiana and Alaska, where AFP has spent big against the incumbents, has diminished. And GOP recruiting successes in New Hampshire and Colorado have added a pair of seats that didn't look like they were in play a year ago.

The news over the past year has not been all bad for Democrats. They have improved their standing in Georgia and Kentucky, where capable contenders for Republican-held seats jumped in last summer. Both races are currently in Cook's "Tossup" category. And as the above map shows, things have gotten better for Democrats in Iowa, where the GOP field has been lackluster. Finally, Mississippi still looks out of reach for Democrats. But they are keeping an eye on it, given the competitive primary there that, depending on the outcome, could mean a more competitive general election.

But overall, things are looking up for the GOP.

As the chart notes, President Obama's approval rating has dropped in the last year. This is due to several damaging developments, most notably the botched rollout of the health-care law. One of the fundamental questions of 2014 is this: Can Democrats replicate the red state success they had in North Dakota and Montana in 2012, where they turned the campaigns into hyper-local contests, or will most races become national referenda, as Republicans hope?

We'll find out in a few months.