There was no love lost this week between state House Democrats and their newest former member, Rep. Mesha Mainor, the sophomore lawmaker who announced Tuesday that she’s leaving the Democratic Party to become a Republican.

Although the announcement took even some in Mainor’s family by surprise, conversations with Mainor and House Democrats quickly revealed that the split was months, if not years, in the making.

Both sides described a caustic, toxic relationship based on Mainor’s refusal to toe the party line and follow established processes within the caucus. But they differed, wildly, on whether Mainor’s repeated dissents were admirable or duplicitous.

Parties always have their rising stars and outliers, but rarely are the divisions this visible and bitter.

The entire episode raises the question of how much ideological wandering or personality conflict Democrats can handle in their ranks — and what Democratic leaders could have done to avoid the train wreck.

The days since Mainor’s Capitol press conference announcing her switch have been followed by a flood of national media coverage and reams of ugly messages on her social media feeds from angry Democrats around the country.

But when I asked Mainor this week how she is feeling about her decision, she responded with emojis of two dancers kicking up their heels. “I’m relieved,” she said.

The break had seemed inevitable for months, particularly after she became the only Democrat to vote for a high-stakes GOP school voucher bill that failed even after Gov. Brian Kemp’s late lobbying effort.

In the moments after the vote, Mainor sat alone in the chamber, visibly ostracized by her party for straying on that vote – and at least a half-dozen big ones before it.

But she traces the bad blood back to her first day in office.

“This happened the moment I walked into the building,” she said. “Atlanta is a cliquish political community and I am not a part of the ‘in’ crowd.”

Along with being a single mom without family connections to politics, Mainor said several sitting House members had endorsed her 2020 primary opponent, Josh McNair, whom she defeated. “When I came into the Capitol, people literally came up to me and said, ‘I will never support you.’”

She declined to say which members said that to her. One Democrat said it was all in her mind. “Nobody was ever out to get Mesha. But she couldn’t read the room.”

Several Democrats in the caucus pointed to Mainor’s early idea to run against then-state Rep. Bee Nguyen, a popular rising star in the party, to lead the Atlanta Legislative delegation. Waiting your turn is expected, they said. But Mainor charged ahead anyway, with more bills and ideas that she never ran past higher-ups.

“What they told me was, ‘You’re a freshman. You don’t get to decide what you’re going to do. You have to run everything through us,’” Mainor said of Democratic leaders. “And I was like, this is for my community.”

Mainor and Democrats clashed so often that year that the late Republican House Speaker, David Ralston, summoned her to his office. By then used to being under fire, she assumed she was in trouble with him, too.

“I went down and he was like, ‘Man, they are giving you a hard time,” she recalled. The chamber’s top Republican encouraged her to keep doing what she was doing. Other senior Republicans kept an eye out for her after they said they’d seen her dressed down by other Democrats on the House floor.

She said she considered not returning to the Capitol the next year.

“I was at church, my pastors were praying for me. I’ve never been so stressed in my life,” she said. But after “the spirit led me” to return, Mainor said a thicker skin and lower expectations of getting along made the next two years easier. “This third year, it didn’t bother me at all,” she said.

Until it did.

Three days after her vote for the Republicans’ voucher bill, state Sen. Josh McLaurin, a Sandy Springs Democrat, tweeted a photo of a blank check with a note that he would put up $1,000 for a primary challenge to Mainor in her Atlanta district. “All I need is a name,” he wrote.

I talked to McLaurin at length this week about why he did that.

“I got involved as a former House member, but for all Democrats in Georgia, because you had a legislator who was actively sowing discontent and disunity among the Democratic caucus, but there was zero public accountability for that until all of this happened,” he said.

McLaurin called her “narcissistic” and predicted Republicans will find “she’s more trouble than she’s worth.”

“She has painted herself as the victim of some kind of relentless Democratic attack to try to drive her out of the party,” he said. “This is more like there was a vase on the edge of a shelf and a handful of us sort of tapped it and then it fell off the shelf.”

All they did, he said, was make the case “in a few words that maybe she shouldn’t serve as a Democrat.”

Mainor started to think the same thing.

“I went into some self-reflection,” she said. “I went to the Republican website and I looked up their platform. And then I reached out to a friend that’s a Republican and he said, ‘Well, do you want to talk to the chairman of the Republican Party?’”

That began a weeks-long dialogue between her and new Georgia GOP chairman Josh McKoon, who has now pulled off a one-seat pickup as one of his first acts leading the party.

“When I spoke to him, he said, ‘Look, we don’t have minorities in the party, and we need a voice and we don’t have anyone really giving us a voice,’” Mainor said of their conversations.

She and a small group of staff discussed the pros and cons of switching parties and decided to make the jump.

But even the execution of the decision left Democrats incensed, including her decision to use CJ Pearson, the former spokesman for Trump-aligned, Democrat-turned-Republican Vernon Jones, as an informal adviser.

State Sen. Michelle Au, a Gwinnett Democrat, tweeted, “Pursuit of attention and favor may be calculated, opportunistic, profitable. But we shouldn’t confuse that with ‘bravery.’”

Mainor said she has no regrets.

She also insists she’s planning to run for reelection in her deep blue Atlanta district, which voted 90% for President Joe Biden in 2020 and where she won the Democratic primary with 65% support. Will voters there really go for a Republican?

Democrats are confident she’ll lose. Mainor, as usual, disagrees.