This was supposed to be a Republican year in the U.S. Senate contests, with better than even odds that Sen. Mitch McConnell (R-Ky.) would take the majority leader's seat from Sen. Harry Reid (D-Nev.) in the 113th Congress.
In January 2012, Democrats were looking at defending 23 seats, with seven incumbents retiring, while the GOP had only 10 seats to worry about, with just two senators retiring in reliably Republican states. To guarantee McConnell would grab the gavel, the GOP needed to pick up just four seats, theoretically powered along by widespread discontent over the economy.
The polls are so close in many states that it could still happen. Even if almost no one thinks it will, the Republicans can still see a path to power in the upper chamber.
"At this point, we'd almost have to run the table in the tossups," said Rich Galen, a Republican consultant and pundit.
To figure out how the GOP could yet win, it's worth looking at what went wrong.
Galen points first to his side's "self-inflicted wounds" in Missouri and Indiana. In the Show Me State, Rep. Todd Akin ran to the right in a three-way Tea Party primary and came out on top. Then he declared that women don't become pregnant from "legitimate rape." Akin apologized, but the damage was done, and he plummeted in the polls, giving the most remarkable opening for Democratic Sen. Claire McCaskill.
"McCaskill was so unpopular in Missouri that if you said she was as dumb as a stump, you'd get in a fight with someone who said it was an insult to the stump," said Galen.
In Indiana's GOP primary, the Tea Party-backed Richard Mourdock ran far to the right of the relatively moderate Sen. Dick Lugar and won, knocking out a candidate who would have been a sure bet for the GOP. Mourdock buoyed Democrats' hopes for their own conservative candidate, Rep. Joe Donnelly, by declaring that he didn't believe in compromise. Then he joined Akin in making ill-chosen remarks about rape, saying pregnancies from such assaults were something "God intended." Mourdock has also crashed in the polls.
Losing those two seats was inconceivable to Republicans a year ago.
In something of another self-inflicted wound, the party lost popular Maine Sen. Olympia Snowe, who grew fed up with the Senate's extreme partisanship and at the end of February became the third GOP senator to decide to retire. Her seat most likely will go to independent former Maine Gov. Angus King, who seems most likely to caucus with Democrats.
In reliably blue Massachusetts, incumbent GOP Sen. Scott Brown has put up a strong fight against a popular Democrat, Elizabeth Warren, but recent polls have her pulling ahead.
If Indiana, Maine, Massachusetts and Missouri all go the way they appeared to be headed this weekend, the Republican Party could lose four seats it had counted on, meaning it needs to flip seven Democratic seats to win control.
There were, theoretically, that many chances this weekend, especially in races where incumbent Democrats had bowed out. Nebraska, North Dakota, Virginia, Wisconsin, New Mexico, Connecticut and, to a much lesser extent, Hawaii could be in reach. Other somewhat reasonable chances for the GOP remain in Montana, Ohio, Florida and just recently Pennsylvania.
Of those 10 contests, though, the only one deemed a likely GOP pickup is Nebraska, where Sen. Ben Nelson is retiring and Democrats are trailing Republican Deb Fischer, even after they convinced the well-known Bob Kerrey to jump into the race for the seat he once held.
All of the other states are tossups or looking like Democratic wins, according to the HuffPost Pollster averages.
There's also one tossup state -- Arizona -- where Republicans had been counting on an easy race. To replace Sen. Jon Kyl (R), they had Rep. Jeff Flake, but he's run into trouble with Democratic challenger Richard Carmona, the former Bush-administration surgeon general. Flake's loss could potentially set the GOP five seats in the hole and give the Democrats a chance at actually gaining seats. Even in Nevada, where Republicans have incumbent Sen. Dean Heller facing Rep. Shelley Berkley, a Democrat freighted with an ethics investigation, the race is nearly tied.
Republicans' chances lie in the hope that the polls are "skewed," as so many of the party faithful have charged this election season. The National Republican Senatorial Committee's executive director, Rob Jesmer, argued to National Journal last week that Republicans are doing better polls than are Democrats and independent pollsters this year.
Essentially, pollsters weight their results to try to reflect the actual breakdown of the voting population. The GOP pollsters have been using a model that looks similar to 2008, while others have projected more population growth. And there have been years when the mainstream polls got it wrong, including presidential polling averages in 1980 (off by 7 percentage points on Jimmy Carter) and in 1996 (off by 5 percentage points on Bill Clinton).
If the GOP survey models are better, then Republicans do have a route to taking back the Senate.
"Despite a few unexpected setbacks, Republicans still have a very real path to the majority and we believe the overall environment is moving in our direction," said Brian Walsh, spokesman for the National Republican Senatorial Committee. "But no one on our side ever thought winning the majority would be easy, and with so many close races right now, it would be a mistake for either party to be over-confident at this stage."
Michael McAuliff covers Congress and politics for The Huffington Post. Talk to him on Facebook.