Maine House Speaker Sara Gideon criticized U.S. Sen. Susan Collins on Monday for her vote in favor of the 2017 Republican tax bill, saying the bill strengthened a lawsuit aimed at repealing the Affordable Care Act.

Gideon is running for the 2020 Democratic nomination to challenge Collins, a Republican who has been in office since 1997. The Cook Political Report, a newsletter that analyzes campaigns, moved the Maine Senate race last week from “leans Republican” to “toss-up.”

“It all comes down to facts, and the fact is Susan Collins voted for this law that has allowed this court challenge to happen, that endangers pre-existing condition protections for people and potentially could throw 20 million people off of their health insurance,” Gideon said in an interview with the Press Herald after speaking at an event in Portland that highlighted the Trump administration’s efforts to repeal the ACA. The Protect Our Care bus tour is barnstorming the country and had two stops in Maine on Monday, in Bangor and Portland. Protect Our Care is a national, left-leaning health care advocacy group.

Gideon, other Maine lawmakers and health care advocates made their case in front of Portland City Hall on Monday.

About 70,000 Mainers have ACA individual health insurance, and an additional 35,000 gained health coverage through the ACA’s Medicaid expansion.

Other Democratic challengers vying to win the party’s March 3, 2020, primary for a chance to unseat Collins include activist Betsy Sweet and Saco lawyer Bre Kidman.

Collins’ support of the 2017 tax cut bill was a key moment paving the way to the bill’s passage in the Senate, with the bill passing by a slim 51-48 margin in December 2017.

The complex tax bill trimmed taxes across most tax brackets but also included a provision to eliminate the penalty for the individual mandate, a provision of the ACA that required people who didn’t have health insurance through an employer or other means to purchase health insurance or pay a penalty.

The individual mandate is at the heart of a lawsuit supported by the Trump administration, which is arguing that the ACA is unconstitutional because Congress removed the mandate’s penalty, making it no longer a tax.

While Collins did not support the individual mandate, she is not in favor of repealing the ACA.

“Sara Gideon is trying to have it both ways. Eighty percent of those who paid the penalty under the individual mandate earn less than $50,000 a year,” said Kevin Kelley, Collins’ campaign spokesman. “Senator Collins has always maintained that is unfair.”

Kelley criticized Gideon for not being clear about whether she supports the concept of the individual mandate.

“Gideon won’t say whether she supports it or not,” Kelley said.

The Gideon campaign didn’t immediately respond to a follow-up question by the Press Herald regarding whether she supports the individual mandate.

Meanwhile, Collins has urged Trump’s attorney general, William Barr, to defend the ACA in court, but the administration continues to press its case to repeal the ACA. Legal experts say the case is likely headed to the U.S. Supreme Court after a federal judge in Texas sided with the Trump administration to toss out the law.

The 5th U.S. Circuit Court of Appeals in New Orleans heard arguments in July. The ACA survived a different constitutional challenge in the Supreme Court in 2012.

In July 2017, Collins bucked the Republican party, joining Democrats and Republican Sens. Lisa Murkowski of Alaska and John McCain of Arizona to preserve the ACA by one vote.

Collins attempted to alleviate the tax bill’s potential to disrupt the ACA marketplace by advocating for bipartisan bills to support ACA stabilization measures. Those bills failed to gain traction in 2018, but some states have passed measures on their own that have helped stabilize ACA markets.

Maine, for instance, restarted a reinsurance program that has helped keep ACA insurance premiums in check.

Gideon said that Maine this year – with Democratic Gov. Janet Mills and a Democratic majority in the Legislature – approved a series of measures that would help protect patients if the ACA is repealed. One of the new laws has enshrined pre-existing condition protections for patients in Maine law.

However, if the ACA is repealed, billions in federal funding for Maine and all the states would vanish.

“This is causing great uncertainty for Mainers and for Americans, threatening our confidence that health care access and coverage will be there when we need it,” Gideon said Monday at the Portland event. “It’s unacceptable.”

Rep. Thom Harnett, D-Gardiner, said everyone deserves access to health care, regardless of income level and what job they have.

“Health care is a basic and fundamental human right,” Harnett said.