One of the defenses of former FBI director James B. Comey in his ongoing battle with President Trump is that he — like most of the other leaders of the investigation into Russian interference in the 2016 election — is a Republican. If special counsel Robert S. Mueller III’s team is hopelessly tainted by having donors to Democratic candidates in the mix, as Trump would argue, what does it say that their boss (Mueller) and his boss (Deputy Attorney General Rod J. Rosenstein) and his boss (Attorney General Jeff Sessions) are all Republicans? If partisanship is more important than professionalism, how can we criticize Comey, given that he too is a Republican?

Well, here’s a bit of kindling for this fire: Comey now says he’s a Republican no longer.

He made that revelation in an interview with ABC News.

“In your heart of hearts, do you still consider yourself a Republican?” asked Brad Mielke, the host of the “Start Here” podcast.

“No,” Comey replied. “The Republican Party has left me and many others. I need no better evidence than their new website — which I think is ‘LyinComey,’ maybe? — attacking me. … I just think they’ve lost their way, and I can’t be associated with it.”

“When did you see that change take place?” Mielke asked.

“Probably over the Trump presidency, and, probably began during the campaign of ’16?” Comey said. “Came to the conclusion that these people don’t represent anything I believe in.”

It’s hard to argue with Comey’s feeling as though the Republican Party doesn’t mesh with his interests when the GOP did indeed create a website calling him a liar. It’s a great encapsulation of the party’s politics at the moment: The Republican former deputy attorney general under George W. Bush is critical of Trump, so the GOP comes at him with both barrels. That’s really Comey’s point: In the Trump era, Trump is paramount.

But his secondary point — that the party has left him “and many others” is a different story. The data isn’t really clear on whether this is happening, but it’s one of those sorts of things that may feel accurate to an individual. Like the guy who gets frustrated with the service at a restaurant and talks to his friends who all agree that they won’t eat there anymore. Seems like a lot of people are bailing on the restaurant, even though it may barely have noticed the protest. Comey joins other notable never-Trumpers in their critiques of how the party has changed, but it’s not clear that the party’s actually bleeding members any faster than it was before Trump.

This is the long-term trend, after all. Americans are increasingly identifying as independents. A decade ago, there was about a three-way split between those who identified as Democrats, Republicans or independents. Now, a plurality of Americans call themselves independents.

Of that group, though, most align with one party or the other. Only about 10 percent of independents don’t generally lean toward the Democrats or Republicans. Generally speaking, more people call themselves Democrats or lean to the Democratic Party than do to the GOP.

The composition of the Republican/lean-Republican group looks like this.

Why’s this important? Because what generally happens is that people who leave one party or the other move into that group of leaners. Comey’s assertion that Republicans “don’t represent anything I believe in” is almost certainly hyperbole born of frustration. The policy goals of Republican Party of 2014 are broadly identical to the policy goals of the Republican Party of 2018. Unless Comey was a Republican only because he thought its sole policy position was “never attacking current or former FBI agents,” it’s hard to believe that he is that firmly at odds with the party’s politics. (Not that it’s unlikely that he now opposes the party given that it attacked him, of course.)

What this means is that we can try to evaluate Comey’s claim about people leaving the GOP by looking at how that pool of Republican leaners has changed. You’ll notice in the graph above that the section that’s light-red (the leaners) has gotten thicker over time.

In fact, the density of the leaners in the Republicans/lean-Republicans group has gotten much larger over the past decade — and has seen an uptick since the beginning of 2017. (The percentage of leaners in the Democrats/lean-Democrats pool is less volatile but has been ticking higher.)

Before the 2016 election, though, the density of leaners in the Republican voter pool had been falling.

How does one shift into that “leaner” pool? There are probably two factors. The first is that ideological polarization within the party might spur some people to leave. The Republican Party is solidly conservative; the Democrats increasingly liberal. The timelines don’t overlap here; the pool of Republican leaners has grown, even as the density of conservatives in the party has stayed constant, but it’s clear that some, like Comey, are driven away over time by ideological homogeneity with which they disagree.

The second factor is that those who give up on one party often hate the other party more. They’re left in no man’s land in our two-party system, feeling dissatisfied with one party and unwilling to join the other.

How many people have left the Republican Party and landed in that space? It’s hard to say. Certainly some, including a lot of prominent Republican voices in the Trump era. But Trump also got more of the vote in 2016 than Sen. John McCain (R-Ariz.) did in 2008 or than Bob Dole did in 1996. Enough Republicans and Republican leaners stuck with Trump after the election to give him a victory.

The Washington Post’s recent poll conducted with ABC News offers a different perspective on Comey’s argument: Most Republicans side with Trump in Comey’s dispute with the president.

If Comey gave up on the Republican Party, Republicans have also largely given up on Comey.