The Washington consensus right now is that Republicans are slight favorites to take control of the Senate in the midterms. FiveThirtyEight's Nate Silver put the odds at 60 percent. Other prognosticators agree. That may be true right now, but there are signs that the calculus could change in the coming months. Democrats may be in better shape than anyone realizes.

That doesn't mean Democrats are in good shape. They still face a number of structural disadvantages this fall, as Talking Point Memo’s Sahil Kapur documented in February. The party is defending 21 seats, compared to just 15 for Republicans, including ones in red states such as Louisiana, Alaska, Arkansas, and North Carolina. Democratic senators Mary Landrieu and Mark Pryor, for instance, are both from deep-red states—Landrieu's Louisiana went for Romney by 17 points, Pryor's Arkansas by 24 points—that don’t like Obamacare. Outside conservative groups, like the Koch brothers’ Americans for Prosperity, are already spending millions of dollars on attack ads against the Democratic incumbents.

Further complicating matters, Democratic turnout historically drops in midterm elections. Democrats also face the “sixth year curse,” which holds that the party of the president struggles during his second-term midterms. Only Bill Clinton gained seats, thanks to a strong economy and overzealous impeachment trial in Newt Gingrich's House. In 2006, George W. Bush lost 30 seats in the House and six in the Senate. In 1966, Lyndon Johnson lost 47 in the House and four in the Senate. Ronald Reagan, Dwight Eisenhower, and Harry Truman all lost seats in both houses during their sixth years.

Thus, regardless of the public’s support, or lack thereof, of the Affordable Care Act, Democrats face an uphill battle this year. But could they pull a miracle upset and actually increase their majority? RealClearPolitics' Sean Trende, the best conservative prognosticator out there, laid out that unlikely scenario in a piece last week: “The way this could occur is fairly straightforward: The Affordable Care Act improves; there’s no massive rate shock for premiums in September or October; and the economy slowly gains ground. This should propel President Obama’s job approval upward, lifting the collective Democratic boat.”

That doesn’t sound like such a long shot. The media narrative about Obamacare seems to have turned a corner since the administration announced eight million signups. Every day, it seems, there is a new survey or report bearing good news about the law. This hasn’t improved the opinion polls yet, but it likely will. After all, support for the law didn’t deteriorate right after the catastrophic launch. It took more than a month to register.