DOVER — Just 11 third-party candidates will appear on ballots this year, the fewest since 2006.

Those independents — eight Libertarians and three Greens — are seeking six General Assembly seats, the state treasurer’s post, two New Castle County offices and a spot in the U.S. Senate.

The number of third-party candidates running for office increased every cycle from 2006 to 2012 but has dropped precipitously since then. Twenty-seven minor-party candidates ran in 2012, with most of those seeking spots in the General Assembly, but that number declined to 18 the following election and then to 15 in 2016.

Those totals do not include candidates for president.

For the first time since its founding in 2000, the Independent Party of Delaware will not have any candidates in the ballot. Party Secretary-General Wolfgang von Baumgart said IPOD tried to recruit a few people but failed to find anyone qualified.

“We’re not interested in running little symbolic campaigns,” he said. “We’re looking for candidates who will actually campaign and have a chance of winning.”

Scott Walker approached the party about running for the U.S. House of Representatives, but party officials declined his offer.

“We decided to sit this one out rather than take that kind of risk,” Mr. von Baumgart said.

Mr. Walker ended up winning the Republican Party nomination for the office but has been officially disavowed by GOP leadership amidst accusations of racism and bizarre behavior.

The Green Party had seven candidates last cycle but has fewer this year for several reasons. One person decided not to run because of health concerns, Chairman David McCorquodale said.

Mr. McCorquodale ran for the 21st Representative District in 2014 and 2016, garnering 19.2 and 17.8 percent of the vote, respectively.

This year, he is not seeking the office because a Democrat has filed, meaning Republican Rep. Mike Ramone won’t be going unchallenged.

“At this point, our object is to get the Green Party noticed, so getting 19 percent of the vote helps,” Mr. McCorquodale said. “Getting 1 or 2 doesn’t.”

2006 had 11 third-party candidates, but one of those was running on both the Democratic Party and Independent Party of Delaware tickets. That candidate, Barbara Lifflander, ended up getting 37.2 percent of the vote, with the vast majority of voters picking her as the Democratic, rather than Independent, nominee.

If only candidates running on one ticket are counted, then 2008 had just eight minor-party candidates.

The Libertarian Party has fielded at least five candidates per election in every one of the last five cycles, peaking with 18 Delawareans seeking a whopping 21 offices in 2012.

Party Secretary Will McVay credited the party’s success in finding candidates to dedicated members, including Nadine Frost, the New Castle County chairwoman and a candidate for U.S. Senate.

Mr. McVay believes the average voters has a cursory knowledge of the party but may subscribe to some common misconceptions about Libertarians, such as that they are just Republicans who want to smoke marijuana.

“We’re not really the radical caricature that we’re represented as,” he said. “We take the positive aspects of both sides and try to be responsible.”

While the Libertarian and Green parties are probably the most well-known third parties nationally, the Independent Party of Delaware is the biggest minor party in Delaware, with about 6,300 members. The Libertarian Party is fourth with a little more than 1,700 registered voters.

About 159,000 Delawareans are unaffiliated.

According to a September Gallup poll, 44 percent of Americans consider themselves independents. That figure has fluctuated widely over the years, increasing from 39 to 44 percent from December 2016 to January 2017 and then falling back to 37 percent the following month, for instance.

From the 2000 general election to Sept. 1 of this year, the percentage of independent voters in Delaware rose from 23.4 to 25.

Paul Brewer, the research director of the University of Delaware’s Center for Political Communication, can’t identify any clear reasons that might explain the decrease in minor-party hopefuls.

“If I had a hunch, it might be that the political landscape’s gotten more polarized over time and in a landscape like that, it might suck out some of the oxygen for third-party candidates,” Dr. Brewer said.

Unlike states like Alaska, Vermont and Maine, Delaware doesn’t have a tradition of electing candidates from outside the two major parties, he noted.

Running as a third-party candidate is unquestionably difficult. Over the past 20 years, no third-party candidate in Delaware has earned more than 6 percent of the vote in a statewide race in which candidates from the two major parties are running. Just four have broken 3 percent.

Third-party candidates often don’t even attempt to raise funds, and they face systemic disadvantages. Some debates, for instance, only allow Democrats and Republicans to participate

Because of that, it can be very hard to spread a party’s message, Mr. McCorquodale said, noting some people see members of the Green Party as “tree-huggers.”

“We are that, but there’s a lot else to our message,” he added with a laugh.

The Independent Party of Delaware has endorsed a few candidates this fall, such as Republican Senate nominee Rob Arlett, and is backing Andrew Webb’s write-in campaign for the House. While the party may not have anyone listed under its name on Nov. 6, it intends to field candidates in 2020.

“It’s a matter of luck. Sometimes you get somebody,” Mr. von Baumgart said.

Third-party candidates

How many minor-party candidates have run for office each election? Below is a tally of the number of candidates and their affiliation for each election cycle dating back to the start of the millennium.

2018: 11 (8 Libertarian, 3 Green)

2016: 15 (5 Libertarian, 7 Green, 3 Independent)

2014: 18 (9 Libertarian, 5 Green, 4 Independent)

2012: 27* (21 Libertarian, 3 Green, 5 Independent, 1 unaffiliated)

2010: 25*^ (10 Libertarian, 10 Independent, 1 unaffiliated, 2 Blue Enigma, 5 Working Families)

2008: 16^ (3 Libertarian, 4 Independent, 3 Blue Enigma, 6 Working Families)

2006: 11^ (2 Libertarian, 8 Independent, 1 Green)

2004: 17* (9 Libertarian, 5 Independent, 3 Green, 1 unaffiliated)

2002: 20 (9 Libertarian, 7 Independent, 2 Green, 1 unaffiliated, 1 Natural Law)

2000: 13 (5 Libertarian, 2 Independent, 1 Green, 2 Natural Law, 3 Constitution)

*Includes candidates running for multiple positions

^Includes candidates running under multiple parties