The Republican field of candidates for president has now entered a winnowing phase where the party's voters are clearly indicating that there are only six viable candidates in the race. From an initial field of 17 candidates, two have dropped out, five are on life support (politically), and four are in stable but critical condition. This has left only Donald Trump, Ben Carson, Carly Fiorina, Marco Rubio, Jeb Bush, and Ted Cruz with any meaningful chance of winning the party's nomination.

The poll numbers went through a major reshuffling right after the second Republican debate, so there's always a chance this could happen again after the next one. A candidate could have a brilliant debate performance and catch fire, and then follow in Carly's footsteps in the polling. It's still fairly early in the race, and anything could indeed happen. This is probably only possible from within the "critical condition" group, though -- those who are currently averaging between 2.4 and 3.1 percent in the polling. These four candidates may get the chance to be on the same debate stage with the top six next time around (assuming they'll be using similar rules to the first two debates), so they'll have the opportunity to have that magic breakout performance when everyone's watching. In order, these candidates are: John Kasich (3.1 percent average in polling), Mike Huckabee (2.8 percent), Chris Christie (2.6 percent), and Rand Paul (2.4 percent). While Paul has been holding steady in the polling over the past few weeks, though, the other three have been slowly slipping.

The "life support" group is probably beyond all redemption at this point. The five whose campaigns are no longer relevant (if they ever were) are: Bobby Jindal (0.5 percent), Rick Santorum (0.4 percent), Lindsey Graham (0.3 percent), George Pataki (0.3 percent), and Jim Gilmore (who isn't even listed on the Real Clear Politics poll-tracking page).

This leaves six viable contenders, all of whom are polling comfortably above five percent. The pundit world has been trumpeting the fall of Donald Trump for quite a while now, and in the past few weeks they've been joyously pointing out that Trump's poll numbers have fallen for the first time. What this fails to acknowledge is that Trump is still leading the pack, and still has poll numbers any of the other candidates would kill for. The only candidate to get within shouting distance of Trump in the polls has so far been Ben Carson. Trump experienced a drop of roughly seven points right after the second debate, but since then he's held pretty steady. Right now, he's averaging 22.8 percent, down only a point or so in the past few weeks. So his much-discussed slide in the polls may already be over -- something the pundits have been largely ignoring.

Something else most pundits have failed to notice is that Ben Carson is also slipping in the polls. Like Trump, Carson is a political neophyte. This means he doesn't have pat answers to every policy question thrown at him. And he's stumbled more than once, which may be having an impact on his overall support. Carson slid around four points at the same time Trump did, but since then he's somewhat recovered, although (like Trump) at a lower level. Carson is currently polling at 17.3 percent, up from 16.3 percent right after his numbers fell.

Carly Fiorina's rise has been overstated in the press, which continues to baffle me a bit. She did turn in two good debate performances, which attracted a lot more voter support, but she has also topped out in the low double digits. She's polling right now at 11.0 percent, down roughly a point in the past few weeks. But she's never gotten as high as Carson or Trump. Maybe the next debate will provide her with another bump, which would truly make her a frontrunner, but for now she's in a pretty distant third, with only half of Trump's support.

Marco Rubio is slowly improving his position after gaining four or five points after the last debate. He's currently in fourth place, polling at 9.5 percent. But the bigger news this far back in the pack is that Jeb Bush has now fallen to fifth place. He was leading the polls not too long ago, and now he's struggling to even stay relevant. That's a big step down for a candidate who wanted to project the image of invincibility. Bush actually improved his numbers a few points after the last debate, but this was at the end of a very long slide downwards. He bumped up to almost seeing double digits again (9.8 percent average), but has again started to fall back over the past few weeks. He's now at 8.3 percent, over a full point behind Rubio. The rumor is that Jeb's team is now doing some heavy opposition research against Rubio, which would make perfect sense considering the position Jeb now finds himself in.

Bringing up the back of the "top six" pack is Ted Cruz, who has been remarkably stable over the past few months. He's polling at 6.1 percent, down a tiny bit in the past few weeks, but Cruz is notable for holding onto this level of support -- with no big spikes upwards or downwards -- throughout all the rest of the campaign drama that's been going on. He's the most stable candidate in the race, although that's kind of faint praise when he's only got enough support to place him in sixth place overall. About the best thing you can say for Cruz is that he hasn't shared the fate of others at his level who have now dropped out of major contention (such as Christie or Paul, for instance).

The Republican nomination race is still wide open, but it also appears to be narrowing down to a choice between six candidates, when voter support is factored in. The top three choices right now don't have a single day of political officeholding experience between them. That's obviously what the Republican base wants right now, seeing as how their combined support is over 50 percent of the Republican electorate. Trump, Carson, and Fiorina have all stumbled verbally in one way or another over the past few weeks, but they all still enjoy double-digit support -- something no other Republican is able to claim right now. While most pundits breathlessly await that one gaffe that will take down Donald Trump forever, I'm paying more attention to Carson and Fiorina -- because I think it equally likely that one (or both) of them could implode spectacularly at some point, given their inexperience at politics. The rest of the media is already writing Donald Trump's political obituary, but methinks that's a little premature. He's still leading the race, after all -- just not as comfortably as he used to.

Ted Cruz's whole campaign is prefaced on Trump's eventual failure. He's poised to swoop in and corral all the Trump voters after it happens, as he has been all along. This is by no means a certain thing -- either Trump's fall, or Cruz successfully picking up all his voters in the aftermath. For now, he's content to stand in the background and maintain the support he's managed so far.

The real fight in the upcoming weeks -- and, likely, in the next debate -- will be between Bush and Rubio. It's very hard to argue to multimillion-dollar donors that you're inevitable when you're sitting way back in fifth place, so Bush will be looking to take Rubio down a few pegs, and thus slink back into fourth place (the highest spot for anyone with any political experience, currently). It'll be interesting to see if any sparks fly between these two in the next debate, that's for sure.

If I were in charge of setting the rules for the next GOP debate, I'd limit the stage to the top six, because I think it'd be much more interesting to hear only from those who really have a shot right now. Obviously, I am not in charge of debate rules, so it's likely that Kasich, Huckabee, Christie, and Paul will be on that stage as well. It is possible that one of these four will catch fire with the voters, but seeing as how they haven't in the first two debates, I don't consider it all that likely. For better or worse, the safe bet right now is that the eventual Republican nominee will be one of those currently in the top six slots.

-- Chris Weigant

Cross-posted at The Huffington Post

Follow Chris on Twitter: @ChrisWeigant