PORTLAND, Maine (AP) — Republican U.S. Sen. Susan Collins seized the opportunity as she spoke from Washington during a debate Thursday to point out that she’s hard at work while Democratic Maine House Speaker Sara Gideon has been unable to get the Legislature back into session since March.

“We’re working. That is in sharp contrast to what Sara did at the state level where she recessed the Legislature in mid-March and has done absolutely nothing since then to respond to the COVID crisis that we have,” Collins said, pointing to $3 trillion in federal COVID-19 assistance.

Gideon retorted that it’s been six months since the Senate adopted any further relief that states and families are waiting for, and she said she was proud of state's response to the pandemic. “Make no mistake, we still need help from the federal government,” she added.

It was one of several tense moments as Collins, Gideon and two independent candidates, educator Lisa Savage and businessman Max Linn, gathered for a fourth debate with less than two weeks to Election Day.

Collins, who has never missed a vote in the Senate, joined by video from Washington because the Senate was in session. The debate's host made it an all-virtual event after Gideon's campaign balked at appearing in person at the planned venue if Collins was appearing remotely.

The closely watched race is the costliest in Maine history — and one of a handful that could tip the party balance in the Senate.

The candidates touched on the massive amount of money in the campaign, on the high cost of college and on health care, among other topics.

During a discussion of the massive amounts of money pouring into the race, Collins pointedly called out Gideon for attack ads that she claimed were deemed misleading by independent fact-checkers.

“I think it’s disgraceful. This is the first campaign I’ve ever been involved in where my opponent has attacked my integrity and distorted and outright lied about my record,” Collins said.

Collins also quipped that Gideon received more money from donors in Portland, Oregon, than Portland, Maine.

Gideon, for her part, sought to link Collins with Senate Majority Leader Mitch McConnell, a Republican from Kentucky.

There can be no progress on improving health care as long as McConnell leads the Senate, and McConnell cannot be removed from his leadership position unless Collins is ousted, Gideon said.

All four candidates agreed that health care is a human right, though they had different ideas for improving health care.

The four also agreed not to challenge the election results if they were to lose fair and square under ranked choice voting.

Ranked voting lets voters rank all of the candidates in order of preference. If no one achieves a majority of first-round votes, then there is another round of voting, aided by computers, in which the last-place candidates are eliminated and the votes are reallocated to the remaining candidates.

Linn continued to hammer away at the major-party candidates, saying they are part of a “rigged system” and a “broken system.” He said only an independent can bring true change to Washington.

Savage, a former member of the Green Independent Party, said that if she wins that she would reenroll to become the first Green senator.

After making pitches for Medicare-for-all and calling climate change an “existential threat,” she ceded part of her closing comments by handing the mic to Hamdia Ahmed, a Black Lives Matter activist from Portland.

"The same people who are condemning rioting should be condemning the pain that is being inflicted on Black people on a daily basis,” Ahmed, a former Somali refugee, said before her time was up.

The debate was hosted by News Center Maine, which has TV stations in Portland and Bangor, in partnership with the Maine Chamber of Commerce.