This pair of 2020 file photos shows incumbent U.S. Sen. Susan Collins, R-Maine, left, and Maine House Speaker Sara Gideon, D-Freeport, right, who are running in the Nov. 3, 2020, election to represent Maine in the U.S. Senate. Credit: AP

The exclusion of two longshots in one debate and the cancellation of another are the latest controversies in the final stretch of Maine’s U.S. Senate race as Sen. Susan Collins and House Speaker Sara Gideon get ready for their only one-on-one meeting on Wednesday.

The Senate race has been marked by record levels of money, with more than $150 million spent by candidates and outside groups, according to federal data. Polling has been relatively steady all year, with Gideon, a Democrat, maintaining a narrow lead over Collins while independents Lisa Savage and Max Linn have generally polled in the low single digits.

Collins and Gideon are set to square off in a final debate before Election Day, hosted by the Portland-based TV station WMTW, on Wednesday. The showdown between the two major-party candidates comes relatively late in the election cycle. As of Monday, nearly 370,000 Maine voters had already cast their ballots, amounting to 48 percent of 2016 turnout.

Debates have been a flashpoint in the Senate race since Gideon won the Democratic primary in July. The day after winning the nomination, Gideon challenged Collins to five debates. The Republican countered with a proposal for 16 debates, an unusual request from an incumbent. But there will be five after another debate between the two was canceled after Collins confirmed attendance but Gideon did not.

WMTW’s decision to include only Collins and Gideon in the Wednesday debate led to complaints from Linn and Savage, whose campaigns filed a complaint with the Federal Election Commission over the weekend, alleging that a debate with only Collins and Gideon amounted to a campaign contribution to the two major-party candidates.

The complaint is unlikely to go anywhere, as the body that would evaluate it does not currently have a quorum and cannot rule on any complaints. Federal election law allows news organizations to decide which candidates they include in debates, though they must use objective predetermined criteria — such as polling numbers — and not party affiliation.

In a response to the Savage campaign, WMTW’s legal counsel said that the station used several objective criteria to determine which candidates were newsworthy, including polling, fundraising and past electoral performances.

Linn and Savage counter that those measures are not consistent with debates in previous elections, when the station has included third-party candidates, though criteria do not have to be the same from one election to the next, particularly since the race will use ranked-choice voting. If the race remains close, supporters of Savage and Linn could decide the outcome.

“With ranked-choice voting, voters in Maine have an opportunity to rank candidates in accordance with their values,” Savage said in a statement. “How can they do that if the media withholds from them vital information about the candidates?”

Debates have given third-party candidates in the Senate race a larger platform when they might otherwise be overshadowed due to massive spending by party candidates, though the polls so far have not shown clear post-debate movement. Collins and Gideon have raised a combined more than $115 million this cycle while Savage, a retired teacher from Solon, has raised about $162,000, and Linn has self-funded his campaign to the tune of $465,000.

The presence of Savage and Linn has at times defused or distracted from the hostility between the two major-party candidates. Savage has taken the opportunity to pitch a progressive agenda including Medicare for All, while Linn was most remembered for theatrical antics in the first two debates though he largely stuck to policy in the last two.

The pair will ultimately participate in five, all televised. It would have been six, but the Portland TV station WGME canceled a debate that would have been on Tuesday. The Bangor Daily News is WGME’s media partner and would have been involved in the debate, but the station was handling scheduling and declined comment.

Gideon’s campaign said the Democrat saved the debate date, but scheduled other events after reaching out to the station for information about the debate and getting no response. The station then canceled the event. Annie Clark, a spokesperson for the Collins campaign, said Collins would have participated in the event and the scheduling issue was “clearly an attempt by Sara Gideon to avoid facing Senator Collins in a one-on-one debate.”

Barring changes, Collins and Gideon will still meet for their debate on Wednesday. The pair have clashed on a range of issues in previous debates, including health care, judicial nominations, Collins’ seniority in the Senate and Gideon’s record in the Legislature.