It started with Fox News's Megyn Kelly calling out Sen. Marco Rubio's (R-Fla.) alleged flip-flop on whether he supports a path to citizenship.

In a new feature for these debates, she cued up a series of clips of Rubio saying, during his 2010 Senate campaign, that an "earned path to citizenship is basically amnesty." When the video reel finished, Kelly asked Rubio why, within two years of getting elected to the U.S. Senate, did he then support a bill that included that very same path to citizenship he apparently opposed?

The question — and Rubio's answer — tipped off a heated and wide-ranging back-and-forth on immigration that included most of the seven candidates on stage in Thursday's seventh GOP debate. The exchanges were fast-paced and, to be honest, confusing for anyone not familiar with the intricacies of the Senate.

But what the candidates said — and accused each other of — got to the heart of the GOP's dilemma on immigration reform. And that is this: There's no easy answer that will fix what most running for president agree is a broken system and yet appease a base increasingly wary of any reform beyond border security.

We did our best to paraphrase and condense the immigration throwdown into each candidates' main points. Direct quotes from the debate are in quotation marks; our paraphrasing is not.

Here's what you need to know, starting with Rubio's response to that video reel implying he flip-flopped on a path to citizenship:

Rubio: What I was talking about in those videos was opposition to a proposal in the Senate that would give an almost instant path to legalization. I didn't like it because it wouldn't first secure the border. As president, I promise I'll secure the border before I do anything else. "We will not go around deporting 12 million people, but we're not going to hand out citizenship cards either."

Former Florida governor Jeb Bush: Well, Rubio sponsored that bipartisan 2013 Gang of Eight bill that passed the Senate in 2013 that allowed for a path to citizenship. But then he "cut and run" from it when the idea wasn't popular. Also, I wrote a book on immigration.

Rubio: "That is the book where you changed your position on the path to immigration."

Bush: "So did you."

Fact-check interlude: Both men have a point about the other switching positions on immigration. Bush has a long and complicated relationship with the notion of a path to citizenship, appearing to support it in 2012 and then in his 2013 book "Immigration Wars," appearing to say the opposite.

As for Rubio, since the immigration reform bill he supported passed the Senate in 2013, he has worked to distance himself from it, saying we should focus first on enforcement.

[Rating the 2016 candidates' many contortions on immigration]

Rubio, going back to his original point: There will never be progress until we can prove to this country — (read: the GOP base that's largely opposed to a path to citizenship) — that we've got illegal immigration under control. That's border security.

Bush: You're trying to have it both ways — appease the base and get immigration reform done. Real leaders — (read: me) — try to forge consensus, no matter how hard it is.

Rubio: But until we enforce our immigration laws we can't get our base on board.

Interlude: It was Rubio's rival, Sen. Ted Cruz's (R-Tex.), turn for the video treatment. Kelly brought up an amendment Cruz introduced to the 2013 immigration reform bill that would strip the bill's path to citizenship. The point, according to what Fox News played of Cruz's comments back then, was to get rid of the citizenship proposal and yet maintain some kind of legal resident status to help immigration reform pass. (Cruz has since said he introduced the amendment as a "poison pill," which is Washington speak for derailing the entire bill, since he said he knew its authors would only support it if it provided a path to citizenship.)

In other words, Cruz said he never wanted that 2013 Gang of Eight immigration reform bill to pass. It's a claim The Washington Post Fact Checker has deemed unrate-able, because it's impossible to get into Cruz's head when he introduced that amendment.

Cruz: Look, I'm conservative. I have a plan for immigration reform endorsed by some of the most conservative folks in Congress when it comes to this issue, like Sen. Jeff Sessions (R-Ala.) and Rep. Steve King (R-Iowa). I support building fences on the border.

Kelly then gave Sen. Rand Paul (R-Ky.), the other senator onstage, the chance to hit Cruz. Needless to say, he took it.

Paul: "[Cruz] is the king of saying 'Oh you're for amnesty. Everyone's for amnesty except for Ted Cruz.'" Well I was there in the Senate when Cruz said "let's take citizenship off the table and then the bill will pass."

Cruz, deflecting a less-worrisome Paul attack into one on his main rival, Rubio: I'm conservative. Sessions and King like my bill. Rubio cosponsored a bill with the potential future Senate Democratic leader, Chuck Schumer (D-N.Y.)

Kelly, giving Rubio a chance to respond, noted that Schumer agrees with Cruz's version of events.

Rubio: "This is the lie that Ted Cruz's campaign is built on." Cruz isn't the anti-establishment candidate he'd have you believe. He's just swaying with the political winds; he even worked for President George W. Bush's campaign once, and Bush supported comprehensive immigration reform that included a path to citizenship. "Now, you want to trump [Donald] Trump on immigration." It won't work, and we can't win with you as our nominee.

Cruz: I oppose amnesty. Rubio doesn't.

[The GOP debate proved being a senator is bad for running for president]

New Jersey Gov. Chris Christie, chiming in to bash the senators on-stage as he has at past debates when thing got heated between Cruz and Rubio: I have no idea what all these Washington creatures just spent the past 10 minutes arguing about. "I feel like I need a Washington-English dictionary converter." Which is why you should elect a governor for president; we're not crazy like these guys.

Expect this debate to continue, over and over again.