In the past few weeks, as Congress has lumbered inexorably toward a government shutdown, we've seen the emergence of a new faction in the Republican Party: The Ted Cruz wing.

So named after the polarizing senator from Texas, the Ted Cruz wing, which is essentially the Tea Party in concentrated form, has been accused of all manner of nefariousness by members of the GOP, from backstabbing Speaker John Boehner (R-Ohio) to acting like "lemmings with suicide vests."

The very public acrimony on display is a significant moment in the ongoing evolution of the GOP, and the latest evidence that its quixotic strategy to "defund" ObamaCare has exposed — and perhaps exacerbated — a huge divide in the party. Indeed, even though the focus has largely been on the grinding stalemate between Democrats and Republicans, the most vicious fighting has pitted Republicans against one another.

The internecine warfare began weeks ago, when it became clear Republicans had no chance of convincing the Democratic-led Senate or President Obama to join them in defunding ObamaCare. With Cruz publicly and privately exhorting Tea Partiers in the House to go through with it anyway, GOP aides called the freshman Texan a "joke" and griped that he was torpedoing the party for his own political gain.

The Republican backlash grew stronger as Congress approached, and then passed, the deadline to fund the government, in large part because the defund position is deeply unpopular with the general public.

Voters, by a resounding 3-1 margin, oppose shutting down the government to block the health-care law, according to a Quinnipiac poll released Tuesday. And by a 74-17 percent margin, they disapprove of how congressional Republicans have been doing their jobs — the GOP's worst marks ever.

Recognizing the strength of their position, Democrats have refused to budge one inch.

"As long as I am president, I will not give in to reckless demands by some in the Republican Party to deny affordable health insurance to millions of hardworking Americans," Obama reaffirmed Tuesday.

While Democrats have been able to remain united throughout the process, Republicans have devolved into intraparty name-calling that could hurt them in the long run.

Here's Slate's John Dickerson on that point:

If Republicans want to stand fast against overwhelming public opinion, unity during the shutdown is critical. They should be singing from the same song sheet, something that goes a little like this: "We acted to keep government open while trying to protect Americans from being forced into a system they don't trust and which has had such problems the president has exempted big business but not regular people." But there is no unity in the Republican chorus. That was clear even before the shutdown began, as Republican senators spoke openly about the folly of the GOP's approach. That's why John McCain, who was one such senator, was tweeting out polling figures that undermine the House Republican cause. So many Republican members have spoken out against the strategy that the Tea Party Express sent out a fundraising appeal asking, "With Republicans Like These, Who Needs Democrats?" [Slate]

Faced with a unified wall of opposition, and mindful of the overwhelming poll numbers, some Republicans have split with the party and said they are ready to throw in the towel.

"We've called their bluff, and they didn't blink," Sen. Jeff Flake (R-Ariz.) told The New York Times. "At this point it would kind of strain logic to assume that going deeper into this when Republicans are likely to get the blame will benefit us more."

Moderates threatened to revolt Monday night and strike an embarrassing blow to House leadership. Though that plan flamed out, more centrist members have since denounced Cruz and his cohorts and insisted the GOP strike a new course.

By some accounts, there are now enough Republican votes for Boehner to successfully bring a clean government-funding resolution to a vote and send it on to the Senate, ending the shutdown. But Boehner has been so "crippled" since Tea Party–aligned newbies in January threatened to oust him from his post, according to National Review's well-sourced Robert Costa, that he hasn't dared to stand up to them since.

"What we're seeing is the collapse of institutional Republican power," Costa told The Washington Post.

Adding to the chaos, powerful outside groups have targeted Republicans who have broken with Cruz. When some Republican senators supported cloture on the first House budget bill — meaning, they merely refused to stall a vote on the bill itself — the Senate Conservatives Fund called it the "ultimate betrayal." Minority Leader Mitch McConnell (R-Ky.), the SCF said, was a "turncoat" who had "surrendered to Barack Obama."

Combined, this has created a no-win situation for Boehner, leaving him, and the party, hopelessly hamstrung. Under fire from both sides in his own caucus, he will eventually have to cut one wing loose and suffer the backlash.

Whatever Boehner decides, it could determine who is in control of the Republican Party: The Ted Cruz wing or what is left of the establishment.