NASHVILLE (AP) — Lawmakers this year have kicked rival colleagues out of office in Tennessee and off the chamber floor in Montana. They have staged walkouts in Oregon and filibusters in Nebraska, where interactions are so fraught that some lawmakers say they're unsure they can work together anymore.

In a year of outsized acrimony at statehouses, it would be wrong to say tensions have never been worse. Legislatures have seen fistfights, unpopular members hounded from office, mass expulsions and even armed confrontations.

Experts say what's different now is that politics can reward sparring and punish bipartisanship, making reelection tougher for those who seek compromise.

Lawmakers "recognize that the general electorate would prefer that they compromise, but they think that the primary electorate wants them to oppose it," said Laurel Harbridge-Yong, a Northwestern University political scientist.

Civility can crumble when lawmakers draw gerrymandered districts or make voting rules that pick political winners and losers. It also erodes, Harbridge-Yong said, when lawmakers debate hard-to-compromise identity and morality issues, including abortion and LGBTQ+ rights. But lawmakers in districts dominated by one party need to stave off internal challengers rather than satisfy the broader voting public, she said.

In Tennessee, Republicans flexed their supermajority numbers to expel Reps. Justin Jones and Justin Pearson, two young Black lawmakers, for protesting for gun control on the House floor with a bullhorn after a deadly school shooting in Nashville. They were booted for violating decorum. Though protesters didn't enter the House floor, some Republicans, including the House speaker, labeled it an "insurrection," akin to the Jan. 6 U.S. Capitol breach.

The ouster of the since-reinstated Democrats gave their party more exposure in the state than it's had in years. Jones and Pearson, along with Rep. Gloria Johnson, who escaped expulsion by one vote, traveled a national TV circuit, visited the White House, and hauled in donations.

But to political observers the conflict showed further erosion of Tennessee's former reputation for conservative compromisers such as former U.S. Sen. Howard Baker — a key figure in holding President Richard Nixon accountable over Watergate.

Republican Gov. Bill Lee, meanwhile, is seeking to keep guns away from people who could harm themselves or others. GOP lawmakers have shown little appetite to consider the plan despite bipartisan appeal in polling.

When majorities grow decisively large, the minority party has no power and can only complain and shout, said John Geer, dean of Vanderbilt University's arts and sciences school. Meanwhile, the majority doesn't need to bargain and is drawn to extreme policies as primary elections become the key to winning.

In a supermajority, the majority and minority parties "are no longer politicians, they become activists," said Geer, also a political science professor.

Lately, Tennessee legislative districts have rarely been competitive, even as more than one-quarter of House seats have changed hands since 2020. Only four races, of 116 House and Senate seats on the 2022 November ballot, were decided by 10 percentage points or fewer. Conversely, 61 House and Senate seats were uncontested.

Geer said Tennessee is conservative, but the GOP drew districts to widen its partisan advantage further. Democratic lawmakers are almost only elected in major cities.

Division can disrupt an entire legislative session. In Oregon, a Republican Senate walkout began May 3 and could continue through the session's June 25 end. The boycott has prevented the Senate from reaching its required two-thirds quorum.

That's preventing a floor vote on a bill to protect abortion rights and transgender health care that GOP senators say is extreme. It's also blocking more than 100 other bills, including a GOP-opposed gun-safety measure that would increase the purchasing age to 21 for semiautomatic rifles.

GOP Minority Leader Sen. Tim Knopp says the boycott will end only on the session's last day to pass "bipartisan" legislation and budget bills. Democratic Gov. Tina Kotek has failed to break the impasse, and could have to call a special session if lawmakers don't approve budgets covering the next two years.

Senators walked out despite voters in 2022 deciding lawmakers could not be reelected with 10 or more unexcused absences. Republican senators are likely to sue over the measure if they're not allowed to register as candidates. Republicans also walked out in 2019, 2020 and 2021.

On June 1, Democrats cited a state constitutional provision to fine senators $325 every time their absence denies a quorum.

"Senators who do not show up need to start returning the hard-earned tax dollars they do not earn," said Senate Majority Leader Kate Lieber.

In Nebraska, a handful of progressive lawmakers filibustered nearly every bill — even ones they supported — to protest legislation targeting transgender minors. The filibuster revealed lawmakers' ideological divides, with yelling, name-calling, crying and refusals to even speak to other lawmakers. Nebraska's single-chamber Legislature is officially nonpartisan and had prided itself on avoiding dysfunction.

Following Tennessee's expulsions, Montana Republicans voted to bantransgender lawmaker Zooey Zephyrfrom the House floor for the rest of the now-completed session. Zephyr was initially silenced after telling lawmakers looking to ban gender-affirming medical care for minors that they would have blood on their hands and exiled for participating in a protest for her right to debate in the House.

Discord in statehouses is hardly new.

A white supremacist militia in 1874 attempted to overthrow Louisiana's Republican government in a New Orleans street battle, retreating only when federal troops arrived. Republicans ejected legislators they claimed weren't lawfully elected and Democrats established a competing body. White supremacist Democrats took control when federal troops departed in 1877.

Not all rifts were racial. Kansas Republicans and Populists in 1893 seated rival Houses. After Populists locked themselves in the House chamber, Republicans sledgehammered open the door and chased out the Populists. Kansas' Populist governor called up the militia, but mostly Republican militiamen refused to obey. The Kansas Supreme Court eventually sided with the Republicans.

And not all breaches are ancient history. In 1960s Georgia, Civil Rights activist Julian Bond won election to the House three times, but lawmakers refused to seat him, citing Bond's opposition to the Vietnam War. A U.S. Supreme Court ruling let Bond take office in 1967.

Even considering past upheaval, Harbridge-Yong said tensions today are "very high" and "concerning" for democracy.

"It's both concerning for how our legislatures function, for people's trust in the government and their view of policies as they're determined by government as legitimate," she said.

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Amy reported from Atlanta. Associated Press reporters Andrew Selsky contributed from Salem, Oregon, and John Hanna from Topeka, Kansas.