Gov. Janet Mills waves during her inauguration in January.

AUGUSTA, Maine — Maine may see its loudest campaign ever in 2020. The new governor will open her second year in office with issue-based tests and Augusta brinkmanship, and she will end it with a battle for party control of the State House.

Here are the storylines likely to dominate Maine politics for the next year.

Two members of Congress will face difficult and historic tests in deeply nationalized and somewhat mirroring environments. This statement isn’t bold, since U.S. Sen. Susan Collins and Rep. Jared Golden of Maine’s 2nd District are already in the middle of hard re-election bids, though it’s difficult to overstate the scope and noise of the races Maine is about to experience as President Donald Trump is expected to campaign hard to try to win the 2nd District again.

The Republican senator already raised more money than any politician in Maine history for the race by September’s end, and more than $10 million has been spent on advertising on the seat. Four Democrats are running for the nomination to face Collins in 2020, led by House Speaker Sara Gideon, who has national party backing in a Democratic-leaning state.

Collins, who became a target for Democrats after her 2018 vote for U.S. Supreme Court Justice Brett Kavanaugh, will seek her fifth term in 2020. Golden, a Democrat narrowly elected last year despite President Donald Trump’s 10-percentage-point victory in 2016, will face a challenge after splitting his votes on two articles of impeachment against Trump this month.

Both incumbents may be hard outs. Collins won two-thirds of votes in 2014. There’s no clear favorite in a three-way Republican primary in the 2nd District. Still, Democrats are buoyed by a Collins approval rating that dropped from 67 percent in early 2017 to 43 percent in 2019’s third quarter as measured by Morning Consult. Republicans hope a pro-Trump lean ousts Golden.

Voters could rebuke the new governor for the first time in her tenure, particularly over the Central Maine Power corridor. One of the main pitches that Gov. Janet Mills and fellow Democrats made to voters in the 2018 election was that they would simply implement voter-approved laws. That included Medicaid expansion, which was stalled by former Republican Gov. Paul LePage and enshrined during Mills’ first days in office.

That was an easy choice, since a judge had already ruled it would have to take effect. But it was also politically popular and rallied Democrats to a common cause. Being in control of government is another matter. Mills now risks the wrath of voters over two polarizing moves.

She backed Central Maine Power’s proposed hydropower corridor through western Maine in February. The project polled badly in March — particularly in her affected home region of Franklin County — and more than 20 towns have either opposed it or pulled support. Opponents are gathering signatures to get a question aiming to kill it on the November 2020 ballot.

Mills will face her first test on the ballot in March, when voters will decide whether to uphold a new law ending nonmedical exemptions for school vaccine requirements. Democrats passed the law as a response to rising opt-out rates, but it drew hundreds of opponents at a legislative hearing in March. These are two very different issues, but the governor is the common thread.

It will be difficult for the outgoing Legislature to craft grand bargains in an election year. While Democrats in the Legislature flexed their muscles plenty along party lines in 2019, Mills perhaps differed most from LePage in a desire to craft grand bargains that served many purposes for politicians and advocates in Augusta.

Among the major party-line shifts were repealing the vaccine exemptions, automatic voter registration, expanding abortion access and a so-called “death with dignity” law. But there also were broad compromises on paid time off, workers’ compensation reform and an alternative to a controversial “red flag” law tying gun seizures to mental health diagnoses.

While many progressives wanted to go further, the end products reflected Mills’ desire to not overstep in the majority. Republicans wanted to mitigate further-reaching proposals. Groups lobbying the Legislature that were opposed to the original proposals were happy to play ball, knowing Democrats could largely do what they wanted otherwise.

Mills has assembled consensus groups to solve big governmental problems, including panels aimed at addressing an annual transportation shortfall and lowering emissions. Already, Republicans have resisted the idea of raising the gas tax without a constitutional change that would bar bonding for roads and bridges in most cases and voiced frustration with Democratic legislative leaders for not allowing more of their bills to move forward in 2020.

Thorny political questions are wrapped up in each of those issues that will be even harder to solve in an election year for legislators making their cases ahead of the 2020 election.

Legislative Republicans have a straightforward case against Democrats, but wresting control in the 2020 election will be difficult. LePage and Republicans stormed to full control of Augusta in 2010, but it only lasted one term as Democrats campaigned against a tax-cutting budget that most of them voted for and gained back both chambers in 2012.

Democrats are likely to face a rebound in 2020. This year, Republicans instantly hammered Mills’ $8 billion, two-year budget proposal. Most grudgingly acceded to a budget just under that mark in June, but it’s going to be a main focus of Republican campaigns.

While they are likely to win seats, it may take a while for Republicans to dig out of their 2018 hole. Democrats flipped 12 Republican seats in the House and four in the Senate en route to commanding majorities in 2018. To win control, Republicans would need to flip 16 House seats and four Senate seats.

Their three top targets in the upper chamber could be Michael Carpenter of Houlton, Ned Claxton of Auburn and Linda Sanborn of Gorham, who all won narrowly in 2018. Another could be Sen. Shenna Bellows, D-Manchester, who won a second term easily in a Republican-leaning district. Hallowell Mayor Mark Walker, a third-term Republican who has run unopposed twice in the Democratic stronghold, said he is considering a run against her.

In the House, Democrats have 18 term-limited members compared with only three Republicans, yet all but four are in relatively safe districts. Democrats look over-leveraged after winning eight Republican-leaning districts last year, but it would take a disaster for them to lose House control.

Michael Shepherd

Michael Shepherd joined the Bangor Daily News in 2015 after three years as a reporter at the Kennebec Journal. A Hallowell native who now lives in Augusta, he graduated from the University of Maine in...