PITTSFIELD -- U.S. Sen. Elizabeth Warren, D-Massachusetts, urged Berkshire County residents Saturday to continue fighting back against Republican-led efforts to dismantle the Affordable Care Act, stressing that their voices have already made a difference.

The Massachusetts senator took aim at President Donald Trump and Republicans, touted her work in Washington and fielded constituent questions during a town hall-style event at Berkshire Community College.

Warren, who focused the majority of her remarks on GOP-led efforts to overhaul the U.S. health care system, urged constituents to remain engaged, to share their personal stories and not let their frustration get in the way.

"People say to me, 'Oh, but it's tiring' and 'we've done this for six months' -- well yeah, nobody said that a fight was easy...you've got to fight because it's the fight that's important. So part of it is, we must persist," she told the estimated 800 people who turned out for the event.

Contending that voters' voices have already made a difference in the health care debate, Warren pointed to what she cast as a shift in Republicans' rhetoric on the issue.

Instead of pushing for a straight repeal of Obamacare, for example, most are now talking about repealing and the law and replacing it with another health care plan, the senator offered.

"The reason is because of you. It's because of people all over this country who said, 'Whoa, wait a minute, do what? Repeal without putting anything in its place?'" she said.

"The conversation has shifted to repeal and replace. And once we got to repeal and replace, then people started looking at: how many folks are going to lose health coverage; what's going to happen to the price of insurance for a middle-class family ... Every piece of it people saw meant that they started saying louder and louder 'No, we don't want any part of this.'"

Although polls show the Republican-backed House and Senate plans to dismantle the ACA are largely unpopular, Warren added, Republicans will likely continue their efforts to move them forward.

That, she said, is why voters in Massachusetts need to reach out to those in other states who can put pressure on GOP lawmakers -- particularly in the Senate -- to oppose the legislation.

"If this isn't a moment to stand up and fight back, then I don't know when it comes," she said, encouraging constituents to join political groups and engage with voters across the political spectrum.

Warren, however, noted that Democrats need to be disciplined and "can't shoot at everything that moves" when it comes to fighting for issues important to them.

"We really have to put our energy in a pointed way on issues that are in front of us. There's so much moving in Washington now, so much (the Republicans) are trying to do -- rolling back protections on the environment, on worker protections, the attacks on union -- it's just one thing after another," she said. "And what that means is...we've got to stay disciplined."

The focus right now, the senator stressed, should be on health care.

Warren's Pittsfield stop marked the latest of several town halls she has held across the state in recent months.

The Democrat similarly addressed constituents in Lowell last month, Ware in May, Salem in April and Framingham and Springfield in March, as well as recently traveled across the state and country promoting her latest book, "This Fight Is Our Fight: The Battle to Save America's Middle Class."

Warren previously discussed issues surrounding income inequality at Berkshire Community College last summer. More than 500 people turned out for the event.