LEWISTON, Maine (AP) — Two Republican state lawmakers, one endorsed by former President Donald Trump, are seeking the chance to try to unseat one of the most conservative Democrats in the U.S. House of Representatives in a Maine district rocked by a mass shooting last year.

The two members of the Maine House of Representatives face each other Tuesday in a Republican primary. They are Austin Theriault, of Fort Kent, who is backed by Trump, and Mike Soboleski, of Phillips, who is also a supporter of the former president.

The winner will face three-term incumbent Democratic Rep. Jared Golden in Maine’s 2nd Congressional District, which has handed an electoral vote to Trump in the last two elections. The district was also the site of a mass shooting that killed 18 in Lewiston in October.

Theriault and Soboleski both vowed to be a stronger protector of the Second Amendment than Golden in the months since the shooting, which motivated Maine Democrats to approve a battery of new gun control laws. Golden, who has also long fashioned himself as a protector of gun rights, came out in support of an assault weapons ban after the Lewiston shooting but has said he would not have voted for changes such as expanding background checks and creating penalties for illegal gun sales.

Economic development, inflation and immigration have also factored into the primary campaign, but gun control is clearly a major factor on voters’ minds, said Mark Brewer, a political scientist with the University of Maine.

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The election also has a chance to shake up the power structure of Congress. Republicans have a slim five-seat edge in the U.S. House, and the Maine election is one of a handful that could change that balance, Brewer said.

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“This is certainly shaping up as one of the top 10 House races in the country, if not the top five,” Brewer said. “It’s an incredibly evenly divided district, and there are increasingly few of those.”

The 2nd Congressional District is far more rural and geographically much larger than Maine’s other district, which leans more heavily Democratic and is based around Portland. The 2nd District is home to many of Maine’s traditional industries, such as papermaking and lobster fishing.

Theriault is a former NASCAR driver who had a major fundraising advantage over Soboleski in the race. Soboleski, however, picked up endorsements from some other Republican state lawmakers.

Both painted themselves as more in tune with the working people of the district. Theriault said on the gun issue “and many others, Jared Golden is not representing the people of the district.” Soboleski said Golden is “focused on moving up the political ladder.”

Golden, a Marine veteran of two wars, has characterized his approach to gun control and other issues as pragmatic and right for Maine.

“In Maine, as elsewhere, the government, the courts and the people must seek a balance between the individual right and the common good,” he said.