Angus King, Maine's 74-year-old junior senator, is seeking a second term against two veritable juniors, Eric Brakey and Zak Ringelstein. The young populists are promoting platforms ideologically to the right and left of the man both view as a career politician.

Brakey, the Republican, is likely to be the biggest threat to the easy reign of the popular former Maine governor. Though he only crossed the age eligibility threshold for the U.S. Senate in August when he turned 30, Brakey has found an audience among Trump voters with an "America first" view on trade, international relations and immigration.

He opposed Medicaid expansion in Maine and has been a proponent of welfare reform. In other areas, he has leaned away from his party, advocating expanded access to birth control, opposing tax incentives for big businesses and pushing for criminal justice reforms, including the elimination of the cash bail system.

As state director for the presidential campaign of Ron Paul in 2012 and an acolyte of the candidate's son, Kentucky Sen. Rand Paul (who reciprocated by endorsing Brakey in this race), he's likely to be a favorite with Tea Party voters.

Speaking with the Tea Party Patriots of Midcoast Maine at a campaign stop in Searsmont last December, Brakey voiced strong support for the Second Amendment, along with the rest of the Constitution, a copy of which he kept in his jacket pocket.

Ringelstein, the 32-year-old Democratic candidate and political newcomer from Yarmouth, is hoping to catch discontented voters at the other end of the political spectrum with a populist platform.

A former public school teacher, Ringelstein and his wife, Leah, co-founded, and later sold, UClass, a web-based tool for educators. At age 28, he was named to Forbes' "30 under 30" list. He has been invited to the White House and has given a Tedx talk opposing standardized testing.

While Ringelstein is an unknown in political circles, he has a well documented history of throwing himself into his work. After selling UClass, he made a run at a country music career, performing under the name Zak Mountain. Earlier this year, he drove to Texas with a pickup truck loaded with toys and blankets for children at an immigration detention center and was arrested when he refused to leave.

Ringelstein's platform leans hard to the progressive, with calls for living wages, investing in public education, a "Green New Deal" and Medicare for all.

King, an Independent who caucuses with Democrats, is highly favored in the race, despite, or maybe irrespective of, being the only candidate not to appear in an online video wearing only a Speedo.

The former two-term Maine governor, attorney and wind-energy entrepreneur, has promoted relatively progressive causes, including renewable energy and affordable health care, that have made him popular with Democrats. But analyses of his voting record by congressional tracking groups show him aligning with both parties almost equally.

King currently sits on the Senate Intelligence Committee, putting him at the center of the investigation into Russia's interference with U.S. elections in 2016.

Brakey and Ringelstein face steep odds — predicts Brakey will get a larger share of the popular vote, but puts both candidates' chances at 1 in 100. The site, which uses polls and other data to predict elections, gave Donald Trump better than 1 in 4 odds before his 2016 upset win.

Brakey has been the underdog before, having won his current seat in the state Senate over an incumbent, John Cleveland.

Both he and Ringelstein could benefit from ranked-choice voting, which will be used this year in Maine's races for U.S. Senate and Congress. The system is intended to minimize strategic clustering around "safe" candidates, allowing voters to pick third-party candidates and underdogs without fear of throwing their votes away.