As they enter the final week of a record-setting campaign, Sen. Susan Collins and Democratic challenger Sara Gideon plan to crisscross the state by bus and by car in search of elusive holdout votes.

With control of the chamber at stake, Maine’s Senate race has shattered state campaign fundraising and spending records – with more than $150 million spent as of last week – and could go down as one of the most expensive congressional contests in U.S. history.

All of that money means the seemingly nonstop negative advertising will continue through Election Day.

The candidates, meanwhile, will be making their cases directly to voters during smaller-scale events, tours and door-knocking campaigns around the state through next Tuesday. The final push is happening at a time when one third of Maine’s 1 million registered voters have already cast their ballots early by mail or through in-person early voting because of the COVID-19 pandemic.

In addition to the two frontrunners, independents Lisa Savage and Max Linn will be holding events as they seek to capitalize on Maine’s use of ranked-choice voting in federal elections.

The stakes are particularly high for Collins, a four-term incumbent consistently trailing behind Gideon in both the polls and fundraising.

Senate votes on President Trump’s latest Supreme Court pick, U.S. Circuit Judge Amy Coney Barrett, kept Collins in Washington, D.C., over the weekend with the final vote expected to take place Monday. Collins has said she would not vote in support of Barrett’s nomination because she opposed replacing the late Justice Ruth Bader Ginsburg so close to the presidential election, although her opposition is not expected to affect the ultimate outcome.

Collins spokeswoman Annie Clark said the senator will resume her “All of Maine” campaign bus tour on Tuesday, which has already logged more than 4,000 miles.

Collins talks aboard her bus during a mid-September tour. “I love this, I really do,” she says. “My bus tour is always my favorite part of the campaign.” She’s running for re-election on experience and the power of incumbency. Shawn Patrick Ouellette/Staff Photographer

“For Senator Collins, the focus of this race has always been on the people of Maine and what she has and can still do for them,” Clark said in a statement. “National Democrats have flooded the state with millions of dollars in false attack ads urging them to vote against their own self interests solely to make Chuck Schumer the majority leader of the Senate.

“We’re confident that Mainers will see through it and reelect Susan Collins – our Senator,” Clark said. “And the person they’ve known for years who leads and delivers on the most pressing issues facing our nation, but who still cares deeply about the individual problems facing every Maine family.”

Gideon, who is currently speaker of the Maine House of Representatives, plans to continue hammering her campaign’s message that “Health care is on the ballot” as she seeks to tie Collins to Republican-led threats to the Affordable Care Act.

Gideon has been holding health care-themed events for weeks, whether touring substance abuse facilities, holding town hall-style events or leading round-table discussions focused on reproductive rights. The latter events have been aimed at capitalizing on lingering anger among abortion rights supporters about Collins’ pivotal vote to confirm Supreme Court Justice Brett Kavanaugh in October 2018.

Over the weekend, the Democrat also began making appearances at vote-canvassing events with volunteers. She is also expected to hold additional health care-related events this week as well as at least one more “Supper with Sara,” which would be the 40th of her campaign.

Democratic U.S. Senate candidate Sara Gideon talks to guests during a campaign event at Crystal Spring Farm in September. Derek Davis/Staff Photographer

“Throughout her campaign, Sara Gideon has made it a priority to meet Mainers in their communities, hearing about the challenges they face, hosting nearly 40 ‘Suppers with Sara,’ and sharing her vision for protecting and expanding access to health care, creating an economy that works for everyone, and making Washington work for Mainers,” a campaign spokesman, Will Simons, said in a statement.

“Less than two weeks from Election Day, Mainers know how important this election is – they’re fired up and ready for new leadership and they’re turning out across all 16 counties to send Sara to the Senate,” Simons said.

Maine’s Senate race is among a handful nationwide that have been in the spotlight for more than a year as Democrats attempt to regain control of the chamber. Both Gideon and Collins have received unprecedented financial support (for a Maine race, that is) from donors giving directly to their campaigns and from outside groups wading into the campaign with advertising.

After reporting a record $39.4 million fundraising haul during the third quarter of 2020, Gideon reported raising an additional $5.9 million between Oct. 1 and 14. Collins, by comparison, raised roughly $8 million during the third quarter plus $1.7 million during the first two weeks of October.

Gideon reported $20.7 million in available funds as of Oct. 14 – more than four times the $4.4 million reported by Collins.

Senate candidates, from left, Lisa Savage, Max Linn, Sara Gideon, and Susan Collins get ready to begin their debate Sept. 11 in Portland. Brianna Soukup/Staff Photographer

Outside organizations have dumped an astonishing $90 million into Maine to support or oppose either Collins or Gideon. That $90 million combined with the $61 million spent by the two candidates to date ranked Maine’s Senate race sixth nationally in total spending behind North Carolina, Iowa, Arizona, South Carolina and Montana, according to a running tally maintained by the Center for Responsive Politics.

With all of that money flooding the small state, the two independents in the race – Savage, a retired teacher from Solon, and Linn, a financial planner from Bar Harbor – have struggled to make headway against Collins and Gideon. But Maine’s use of ranked-choice voting on the ballot means their supporters could help sway the election if neither of the frontrunners wins a majority on the first vote tally.

On Wednesday, WMTW-TV will hold a televised debate between Collins and Gideon – the final one before Election Day. The station did not invite Linn or Savage, however, prompting the two excluded candidates to lodge a formal complaint with the Federal Election Commission.

Savage said she will spend the next week continuing to talk about Medicare for All and a demilitarized Green New Deal that calls for shifting production at defense contractors – including Maine’s Bath Iron Works shipyard – toward clean energy and green infrastructure projects.

In an interview, Savage said she will focus most heavily on the 18- to 35-year-old segment of voters, many of whom she said are frustrated with the two-party system. During street events in Portland, for instance, Savage and her campaign have been handing out condoms calling for Medicare for All, which she said “have been a big hit.”

Ranked-choice voting would allow voters to express their support for Medicare for All by ranking her first and then Gideon as second. Gideon supports adding a “public option” for Medicare to the Affordable Care Act.

“It’s a motivational message to seize the ranked-choice voting moment and be able to truly express your vote in a way that wasn’t possible before ranked-choice voting,” Savage said.

Linn attended Trump’s last-minute rally in Levant on Sunday and plans to hold private campaign events at homes in Aroostook, Hancock, Penobscot, Washington and York counties before Election Day, according to spokesman Matt McDonald.

Linn also plans to continue television, radio and print advertising as well as what McDonald described as “an aggressive email campaign.”