Mitch McConnell stands out as the big loser tonight after his party again failed to take advantage of a Senate race map that favored them and McConnell’s ascension to the Majority Leader post.

Instead, the Kentucky Republican finds himself in the exact same place that he did yesterday — as the Minority Leader pitted against a Democratic president.

Despite defending just 10 Senate seats to the Democrats’ 23, the GOP made a series of missteps that put the Senate majority out of reach for McConnell and even resulted in the party losing two of their own seats to Democrats and one to a Democratic-leaning Independent.

Richard Semiatin, assistant professor of government at American University, said much of problem stems from conservative primary challengers — backed by outside groups — who beat out more mainstream Republicans who would have stood a better chance in the general election.

“I think it’s a function of what’s happening within the Republican Party and the fight over the soul of the Republican Party,” Semiatin said.

Conservative GOP candidates won primaries in Missouri and Indiana, but the losses by Rep. Todd Akin in Missouri and Richard Mourdock in Indiana appeared largely preventable. Both candidates dropped in the polls — Akin precipitously — when they made controversial remarks about rape victims. Both were defending their positions that abortion should be illegal even in cases of rape and incest.

McConnell now heads into the lame-duck session with a conference that will be strong enough to mount a filibuster, but without any arguable mandate that could change the shape of the debate over the looming fiscal cliff. Democrats have largely assumed that their ability to hold onto control of the chamber would work to their advantage in convincing Republicans to capitulate on raising taxes for higher income taxpayers. But House Republicans have already made it known that voters who returned them to power gave them just as much of a mandate to block such tax increases.

On Tuesday night, Speaker John Boehner (R-Ohio) declared that the GOP’s success in retaining their House majority means voters do not want tax increases.

It’s likely McConnell will seize on that talking point as a reason to hold firm against Democratic proposals to deal with the fiscal cliff, which would hit in the new year if Congress doesn’t address expiring Bush tax cuts, deep automatic spending cuts and a debt ceiling hike.

McConnell famously declared that his top goal was to make Obama a one-term president. With that issue no longer a factor in his calculations, some sources in both parties have predicted more cooperation between the parties going forward.

One issue that could create a snag is McConnell’s own 2014 race for re-election. He has been moving aggressively since 2010 to ensure that he does not draw a primary challenger, and that has meant tying himself more closely to tea party favorite Sen. Rand Paul (R-Ky.) — who won his primary despite McConnell’s support for his more mainstream opponent. A desire to continue tacking to the right could factor into McConnell’s calculus on whether he should pursue a greater spirit of cooperation with Majority Leader Harry Reid (D-Nev.).

McConnell’s lost opportunity Tuesday brings back memories of when Republicans came close to taking back the Senate in 2010. While the tea party helped Republicans win control of the House, the conservative movement was not able to put candidates in Colorado, Delaware and Nevada over the finish line. If they had, Republicans would have secured 50 votes in the Senate, a minority only by virtue of not holding the vice presidency.

Experts also chalk up Republicans’ coming up short to a slate of relatively strong Democratic candidates and the fact that turnout, which favors Democrats, is stronger in a presidential election.

“This is not an all-star list of Republican candidates … and Democrats have done a decent job of recruiting,” said Sarah Binder, a Congressional expert and professor at George Washington University and senior fellow at the Brookings Institution.

Republicans picked up at least one seat in Nebraska, but lost seats they held in Indiana, Massachusetts, and Maine. They also were unable to flip vulnerable Democrat-held seats, such as the tightly contested Virginia Senate seat won by former Democratic Gov. Tim Kaine.

Binder noted that Democrats also got a big boost with the retirement of Sen. Olympia Snowe (R-Maine), which allowed them to, in essence, win the seat because independent former Gov. Angus King is expected to caucus with Democrats.