AUGUSTA — The Democratic and Republican primaries for Maine’s open congressional seat have been dominated by one question: What’s more valuable in the state’s representative, political purity or a knack for compromise?

Democratic rabble-rouser Troy Jackson and tea party-backed Bruce Poliquin hope their pledges to stand up to the opposition will propel them to victory in the 2nd Congressional District on Tuesday.

Liberal dealmaker Emily Cain and establishment Republican Kevin Raye are counting on voters to embrace their messages that they will help mend divisions in Congress with their ability to reach across the aisle.

With the political battle lines drawn, the focus is on voter turnout. The four candidates are traveling throughout the massive district – which covers most of Maine except for a swath of land on the southern coast – to urge their supporters to get to the polls.

“Turnout is going to be key here, and what I think will really be important is which of these candidates have the most effective turnout-generating plan and game,” said Mark Brewer, a political science professor at the University of Maine.

In the Democratic race, Jackson, a state senator and logger from Allagash, accused his opponent of talking like a Republican. He questioned why she’s one of the few Democrats who have been able to work well with Republican Gov. Paul LePage, and he criticized her support of the governor’s $400 million in tax cuts in a 2011 budget.

But Cain, who serves in the Senate with Jackson and works at UMaine, said being a fighter who’s unwilling to compromise will only lead to more gridlock. She has combated Jackson’s claims by pointing to his straying from the party on social issues.

Jackson opposed gay marriage in the Legislature in 2009 and has supported measures backed by anti-abortion groups.

On the Republican side, Poliquin, a businessman and former state treasurer, portrays his foe as a “liberal” who’s willing to cave on Republican values, pointing to his decision against taking a pledge not to raise taxes.

But Raye says his opponent will only add to the dysfunction in Congress. The former state Senate president and chief of staff to former U.S. Sen. Olympia Snowe touts his leadership in being able to win bipartisan support to advance tax cuts and pension reform in Augusta.

While Jackson and Poliquin have used similar tactics against their opponents, the nature of the Republican electorate and anticipated lower-than-normal turnout may give Poliquin a better chance, said Sandy Maisel, political science professor at Colby College.

Republican primary voters across the country have been more likely to choose candidates who represent extreme wings of the party while Democrats have looked to candidates better poised to win a general election, he said.

The 2nd District races are the biggest draw of Tuesday’s election with uncontested primaries in the Senate, 1st Congressional District and governor’s races. Turnout is expected to be low – 13 percent to 15 percent of eligible voters, said Secretary of State Matthew Dunlap.

Jackson is focusing his efforts in the final days in Androscoggin County, which his campaign believes is up for grabs since neither candidate has roots there. Cain plans to be there Monday before heading to Bangor and Orono on Election Day.

Poliquin’s campaign says he’ll be calling and visiting voters to encourage them to get to the polls. Raye is spending Monday in Aroostook County before visiting Lincoln and Millinocket.

On Tuesday, all four will be eager to see if it voters choose the fighters or the compromisers in each party to square off in November.