Democratic leaders in Congress are encouraging their members to hold rallies against Republican plans for eliminating the Affordable Care Act (ACA) under President-elect Donald Trump on the final weekend before his inauguration.

The plans came from a “Dear Colleague” letter from the next Senate Minority Leader, Chuck Shumer, D-New York, House Minority Leader Nancy Pelosi, D-Caliifornia, and U.S. Sen. Bernie Sanders, I-Vermont, sent Dec. 28, 2016. The letter warned Republican majorities in both the House and Senate will likely “ram through a budget bill that will severely undermine the healthcare needs of the American people” in the weeks between the new Congress being sworn in and Trump taking office.

The strategy expected from Republicans is to try and repeal parts of the ACA through a process called budget reconciliation, allowing the legislation to avoid a Democratic filibuster in the Senate. Only parts of the ACA that deal with government spending and revenues would be affected, but those provisions include major pieces of the law, such as the individual and employer mandates, subsidies for buying private insurance and rolling back the expansion of Medicaid.

Researchers from the Urban Institute warned this strategy would have dire consequences for the healthcare industry, increasing uncompensated care costs by an estimated $1.1 trillion while increasing the number of Americans without health insurance by almost 30 million.

Additionally, the letter said the Republicans will attempt to convert Medicare “into a voucher program” and warned of pharmaceutical prices increasing by “more than $1,000 per year” on seniors and people with disabilities.

To combat this strategy, the letter asked Democrats to organize local rallies and events against Republican healthcare proposals for Jan. 15, five days before Trump is inaugurated.

Trump repeated his campaign attacks on the ACA, pointing to one state’s large average hike in benchmark premiums for 2017.

“People must remember that ObamaCare just doesn't work, and it is not affordable—116 [percent] increases (Arizona),” Trump tweeted on Jan. 3.

He also called the ACA “lousy healthcare” in another tweet referencing Minnesota Gov. Mark Dayton, a Democrat, calling the premium hikes “unaffordable.”

Trump has also said he wants to keep some parts of the law, like the ban on insurers denying coverage based on pre-existing conditions. Without the individual mandate to buy health coverage, however, the Urban Institute said Trump’s strategy could lead to an insurance death spiral, with customers ceasing to pay their premiums and insurers fleeing the individual market mid-year or opting out of participating in 2018.

With the new Congress convening on Capitol Hill, ACA repeal appears to be the top priority. The Hill reports Vice President-elect Mike Pence will strategizing with House Republicans on a strategy, while Democrats will meet with President Barack Obama to discuss ways to defend the law.