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New year, new fights.

As state legislatures across the country prepare to go into session, lawmakers on both sides of the aisle are primed to tackle — and clash over — specific solutions to new problems and old troubles that haven’t been dealt with.

Progressive legislators are focused on legalizing marijuana and passing gun control, while conservative lawmakers are prioritizing measures dealing with reining in unions and immigration.

Here's a look at the coming wars in U.S. Statehouses.

On the left...

Workers' rights: With many states raising their minimum wage in 2017 (at least 18 states and 20 cities began the new year with pay hikes), progressive lawmakers have turned their attention to issues of workers' rights like paid family leave and "fair scheduling."

Legislation mandating paid family leave (for the birth of a child or a serious medical condition) is expected to advance in Colorado, Delaware, Illinois and Minnesota, according to the State Innovation Exchange (SIX), a progressive policy shop. Proposals being circulated in those states closely resemble a bill passed in Washington state in 2017, under which employers and employees pay into a system to cover 12 weeks of paid leave.

State Rep. June Robinson, D-Everett, gives a kiss to Gov. Jay Inslee after he signed Senate Bill 5975 into law which establishes paid medical and family leave on July 5, 2017 in Olympia, Washington. Steve Bloom / The Olympian via AP

In addition, Democratic lawmakers in Connecticut, Maryland, Massachusetts and New Jersey are expected to reintroduce so-called fair scheduling bills after the proposals failed during 2017 sessions. The measures require retail and food-service companies with 500 employees or more to make fixed work schedules available to employees with two weeks notice. They are closely modeled after a first-in-the-nation Oregon state law passed last year, said SIX’s Sam Munger, the group's director for strategic engagement.

Bump stocks for guns: Following the lead of Massachusetts — where the Democratic-controlled state legislature banned rapid-fire "bump stocks" in November — lawmakers in several other states are seeking similar prohibitions against the devices in their 2018 legislative sessions.

A state-level movement to ban the devices took off in 2017, amid congressional inaction on the issue following the mass shooting in Las Vegas that left 58 people dead. The devices effectively turn a semi-automatic rifle into one that fires like a fully automatic weapon by using its forceful recoil to quickly re-engage the trigger mechanism.

Democratic legislators in Arizona have introduced a bill that would ban the sale of bump stocks, while the Denver City Council is scheduled to vote on a city-wide ban on the devices later this month. Republicans have often opposed such measures.

In New Jersey, the Democratic-controlled legislature passed a ban on the sale of bump stocks this month, and Gov. Chris Christie, a Republican whose last day in office is Tuesday, must now decide whether to sign in. If Christie doesn't, his Democratic successor, Phil Murphy, will.

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Pot: Last week, Vermont took another step toward becoming the first state to legalize the use of recreational pot via legislation (instead of by ballot initiative or referendum) after the state's Democratic-controlled legislature passed such a measure; Gov. Phil Scott, a Republican, is expected to sign it.

At least another 11 states will likely debate similar bills in the 2018 sessions.

A budtender shows cannabis buds to a customer at the Green Pearl Organics dispensary on the first day of legal recreational marijuana sales in California, on Jan. 1, 2018 at the Green Pearl Organics marijuana dispensary in Desert Hot Springs. Robyn Beck / AFP - Getty Images

To date, eight states and Washington, D.C., have legalized the possession of small amounts of recreational pot, while 29 states, Washington, D.C., Guam and Puerto Rico have legalized medical marijuana.

Voter registration: Progressive lawmakers want to make it as easy as possible for voters to cast ballots, and are increasingly looking to Automatic Voter Registration (AVR) to do so. The measure has not been embraced by Republicans.

Under most AVR measures, state residents are automatically registered to vote when applying for or renewing their driver's licenses.

In 2017, 32 states introduced bills to implement or expand AVR, according to the Brennan Center for Justice. And this year, Democratic lawmakers in Washington state and Massachusetts are set to introduce measures modeled after a 2015 landmark AVR law in Oregon that automatically registered state residents with drivers' license to vote, according to SIX’s Munger.

And on the right ...

"Right to work": Republican-controlled legislatures in New Hampshire, Pennsylvania, Montana and Ohio are poised to take up right-to-work proposals, which would effectively prohibit employees in unionized workplaces from being required or compelled to join unions as a condition of employment.

At least 28 states already have such laws on the books, and 2018 "will see additional momentum on that front," said Jonathan Williams, the chief economist at the American Legislative Exchange Council (ALEC), a conservative nonprofit that helps draft state bills for GOP lawmakers.

Democrats fiercely oppose such measures.

Public employee pensions: States are increasingly falling behind on their pension obligations to public employees. New Jersey, Kentucky and Illinois, for example, are among a growing group of states that have allocated less than half of what they need to to pay pension costs for their public employees.

Republican-controlled legislatures have begun addressing the issue with urgency. Last year, Republican lawmakers in Pennsylvania worked with Gov. Tom Wolf, a Democrat, to enact a law that automatically enrolled state workers in 401(k)-style plans, instead of traditional pensions.

The state capitol building is shown on Dec. 12, 2012 in Lansing, Michigan. Carlos Osorio / AP file

Legislatures in several more states are planning to take up similar pension reform bills in 2018, with Kentucky leading the charge. Gov. Matt Bevin, a Republican, delayed a vote last fall on an overhaul modeled after the Pennsylvania bill amid pressure from retiree groups, but has vowed to tackle the issue early this year.

"Sanctuary city" crackdowns: Emboldened by a president that has taken a tough stance against immigration and sanctuary policies, conservative-controlled state legislatures are moving to punish so-called sanctuary cities in 2018 sessions.

In Florida, for example, the GOP-controlled House is expected to pass a bill that would require state and local law enforcement departments to cooperate with stricter federal immigration officials. The bill would also penalize local and state officials who don't comply with federal immigration rules, slapping individuals and offices with $5,000-a-day fines. The Florida Statehouse passed a similar bill last year, but the latest one is tougher and could have a better shot at advancing to debate in the state Senate.

Meanwhile, Georgia’s GOP-controlled legislature enacted two contentious anti-immigrant laws in 2017. One made it more difficult for legal Georgia residents who are not U.S. citizens to obtain driver's licenses, while another imposed financial penalties against private colleges and universities that don’t cooperate with federal immigration officials.

Similar proposals could be introduced in 2018 sessions in at least a half dozen other states.

Bipartisanship?

Opioid crisis: Democrats and Republicans are likely to work together on at least one legislative priority this year: curbing the harrowing national opioid crisis.

Hundreds of bills related to the topic were introduced in all 50 states last year, and each has enacted at least one piece of legislation addressing the crisis in some way since 2016, according to the National Conference of State Legislatures.

Expect 2018 to be no different.

Various solutions are being proposed, including increased access to Narcan, the anti-overdose drug, as well as better and increased access to community-based treatment for addicts, tougher licensing for pain clinics, immunity for people who call for emergency assistance, and, critically, stricter guidelines for prescribing opioid painkillers.