Imagine what the numbers will be after the inevitable GOP cave on the debt ceiling.

This is the first time Gallup finds a significantly higher percentage of Republicans than Democrats in favor of a third party. During much of President Bush’s term, the opposite was true, with Democrats more likely to favor the formation of a third party. That gap narrowed in 2007, after the Democrats’ victories in the 2006 midterms, and there has been a minimal difference between the two parties until the current poll.

The increase in Republican support for a third party since 2008 could be an outgrowth of the Tea Party movement, which is closely aligned with the GOP. The poll, which also assessed Americans’ orientation toward the movement, finds 60% of those who identify themselves as Tea Party supporters in favor of a third party, compared with 44% of Tea Party opponents. The opinions of those who say they are neither supporters nor opponents fall in between those of the two groups.

The partisan trend lines are dramatic, especially the GOP’s, but curiously — and despite heavy tea party support for a third party — there’s no corresponding split in ideology. Liberals, moderates, and conservatives are all at either 51 or 52 percent, and support for a third party has declined among all three groups since last year. What gives?

My assumption is that partisan support for a third party should spike when a party is out of power and has nothing to lose by splitting (or flirting with splitting) over ideology. That’s what you’re seeing, I think, in the Democratic trend line from 2003 to 2006: Anti-war liberals were frustrated that their leadership hadn’t done more to check Bush and to convince the public that progressivism is the truth, the light, and the way, so they fantasized about going rogue. Once Democrats took back Congress, they put that aside and focused on influencing the new congressional majority. And indeed, you see a dip from 2006 to 2008, when Pelosi took over and everyone rallied behind their party’s nominee in a presidential election year. Conversely, partisan support for a third party should crater when a party is in power and looking to hold together to preserve its legislative majority — or so I would have guessed. But neither the Democratic nor the Republican trend line follows that prediction. From 2008 to 2010, despite total control of government, Democrats’ support for a third party rose seven points. Republican support for a third party also rose by seven points when they had total control of government from 2003 to 2006; my hunch is that’s because conservatives rallied around Bush after 9/11 and the invasion of Iraq, which artificially depressed third-party support at the beginning of the decade. But check out the numbers from 2010 to 2011, after the great tea party tidal wave: An increase of five points, notwithstanding the fact that Boehner and company now have de facto veto power over the Democratic agenda.

The takeaway here, I assume, is that neither party’s base trusts its leadership much anymore. Republicans are probably irritated at the slow pace of spending cuts after the big GOP victory, especially after Boehner had to come down from his $100 billion pledge in reaching a deal with Obama and Reid. Democrats, meanwhile, were disappointed in Obama’s first two years in office, maybe because of the economy’s sluggishness (the stimulus wasn’t big enough!), maybe because he’s basically been Bush 44 on most counterterrorism matters, or maybe because ObamaCare isn’t quite the single-payer socialist system (yet) that they’ve dreamed about. Granted, their support for a third party cratered after the GOP’s victory in November, but I take it that’s less because of newfound satisfaction with O than from abject terror that the country’s turned against their agenda and therefore they can’t afford to dilute their strength at a precarious moment. And yet, and yet, I can’t reconcile any of that with the stasis in the numbers by ideology. Shouldn’t conservative support for a third party be leaping from disappointment with the House on budgetary matters? In fact, it’s actually dropped slightly since last year. Any theories?