Thousands of demonstrators flooded Boston's famed Faneuil Hall on Sunday (15 January) to join several members of the Massachusetts delegation to Congress and Boston Mayor Martin Walsh to protest Congressional Republicans' plan to repeal the Affordable Care Act (ACA). For nearly three hours, demonstrators – young and old – stood outside in the biting cold to hear the lawmakers speak.

Walsh spoke first, riling up the crowd of an estimated 6,000 people. The Boston native argued that millions of the most "vulnerable citizens" will be "devastated" by the repeal of the Affordable Care Act.

"Defunding Planned Parenthood means both men and women won't be able to access the life-saving STD testing and treatments," Walsh added. The mayor noted that 1.5 million women in Massachusetts will no longer be able to afford birth control if the healthcare bill is repealed.

"We can't stand by and let this happen," Walsh told the massive crowd. "And we won't. Especially not here in Boston or in Massachusetts."

Walsh, who is seeking re-election in the autumn, told attendees he would be heading to Washington DC later this week to meet with mayors from across the country to figure out how to "hold Congress accountable." The staunch Democrat noted he would not be attending President-elect Donald Trump's inauguration.

Lawmakers also welcomed a number of guests to the stage. Kate Walsh, the CEO and president of Boston Medical Center, claimed healthcare services provided by her hospital and others throughout the state were "gravely in danger" by plans to repeal the ACA.

Following a brief speech by Kate Walsh, Mayor Walsh introduced the clear champion of the day: Senator Elizabeth Warren. Warren, a progressive darling who has not shied away from criticising Trump, received the loudest applause.

"We are here today — thousands strong in Boston, and at more rallies all across this country — because we will make our voices heard," Warren said. "If Republicans try to rip healthcare out of the hands of millions of Americans, we will fight them every step of the way."

A running theme throughout the rally was the affect a repeal of the ACA would have on individuals with a pre-existing condition. Under the healthcare law, individuals with pre-existing conditions, such as cancer, cannot be refused coverage by insurance companies or be charged more for their insurance.

Save the ACA
A protester holds up a sign in favour of Obamacare (Affordable Care Act) during a rally in Boston, Massachusetts on 15 January 2017 Nicole Rojas/IBTimes UK

Carole Marcacci, who attended the rally with her husband Eric Hilfer, called Warren "our champion" and told IBTimes UK she was proud of the work the senator has done. The couple from Acton, Massachusetts said participating in the rally was "crucial" and that they believe the Republican plan to repeal the healthcare law is "criminal".

Marcacci accused House Speaker Paul Ryan of wanting to "bring down the social safety net," but added she "won't let that happen". She said that the GOP's plan to repeal the ACA without a replacement is purely political. Marcacci said the ACA was born from Romneycare – Mitt Romney's healthcare plan in Massachusetts – and that the only reason the GOP wants to repeal it is to "obliterate" Obama's legacy.

Warren was joined by nearly the entire Massachusetts delegation, including Senator Ed Markey and Representatives Richard Neal, Jim McGovern, Niki Tsongas, Joseph Kennedy, Katherine Clark, Seth Moulton and William Keaton. The Boston Globe noted that fellow Democratic Representatives Mike Capuano and Stephen Lynch were not present.

Similar rallies were held throughout the US, with Democratic leaders and Vermont Senator Bernie Sanders leading the way. The day of demonstrations came on the heels of significant progress made by Republicans as the inch closer to repealing the ACA. Meanwhile, President-elect Trump announced he is working on a replacement and promised "healthcare for everyone".