Midterm identity crisis: on election eve, the two major parties don't seem to know who they are any more.

• Author: Shackford, Scott
• Position: Republican Party and Democratic Party

In the run-up to the 2006 midterm elections, voters had grown weary of a second-term president with his large-scale domestic bungles (like Hurricane Katrina) and never-ending wars in Iraq and Afghanistan. As punishment, they stripped the president's party of majority control over both House and Senate.

Eight years later, voters have grown weary of a second-term president with his large-scale domestic bungles (like Obamacare) and never-ending wars in Iraq and Afghanistan. (And Syria. And Libya.) The big question for the 2014 midterms is whether the opposition party, having already retaken the House of Representatives, will gain a majority in the Senate as well.

For much of the summer, nearly every independent analyst predicted that the GOP would narrowly re-take the Senate in November's elections. At the start of September, popular political prognosticator Nate Silver gave the Republicans a 62.2 percent chance of taking majority control of the body. But as the month wore on, the likelihood of Republican restoration inched down to 58.5 percent.

Even though Americans continue to be depressed about the weakest economic recovery in the post-war era, and even though they consistently tell pollsters that they are fed up with the political status quo, it's still a coin flip as to whether Republicans will be able to take advantage of the dissatisfaction. One possible explanation for the hesitation is that the GOP, after a raucous six years of internecine struggle, still appears to be philosophically mixed up.

Efforts to replace milquetoast GOP incumbents with fire-breathing Tea Party conservatives largely failed in the 2014 primary seasons, with the notable exception of the scalp collected from House Majority Leader Eric Cantor (R-Va.). Establishment stalwarts Mitch McConnell of Kentucky, Lindsay Graham of South Carolina, and Lamar Alexander of Tennessee easily swatted down insurgent efforts to dislodge them.

But the establishment also suffered losses during incumbent-challenging season, most notably in the expensive, nasty campaign to dislodge Rep. Justin Amash (R-Mich.). Amash, a staunch anti-interventionist and privacy advocate who has emerged as the leader of the House libertarian faction, squared off against primary insurgent Brian Ellis, who was backed by such establishment conservatives as Karl Rove, Rep. Mike Rogers (R-Mich.), and Michigan's Chamber of Commerce. After a campaign that called Amash "Al Qaeda's best friend," Ellis lost by 15 percentage points, causing Capitol Hill's Liberty Caucus to breathe a collective sigh of relief.

Even though Congress has repeatedly hit new lows in public opinion polls over the past few years, only four House incumbents, and no incumbent Senators, lost their primaries. But the challenges to party orthodoxy keep coming, on issues ranging from gay...