(CNN) These days, Deborah Johnson is on edge. She says she's worried she won't qualify for Social Security disability benefits, anxious about her middle son's recovery from a car accident last year, and feeling the pervasive effects of her complex post-traumatic stress disorder that dates back to an abusive childhood.

But by her mid-morning coffee on a recent Thursday, Johnson was feeling pretty good. Her phone call to Republican Sen. Lamar Alexander's district office had gone through.

"I usually get a voicemail, but I talked to a staffer," Johnson, 39, told CNN at her home in Murfreesboro, Tennessee. "And I said I wanted a call back and he wouldn't take my number and I said, 'You're going to take my number. I'm one of his constituents.'"

Her urgent message: Repealing Obamacare would devastate her family.

As mass demonstrations against Trump and his policies are cropping up on issue after issue, Johnson and others like her are becoming the vanguard of a backlash against the dismantling of Barack Obama's legacies, particularly the Affordable Care Act. The resistance to overhauling the law comes just three months after disgust with Obamacare and the perception of government overreach helped vault Trump into the White House.

The increasingly blunt outcry from Democrats has already rattled congressional Republicans and likely extinguishes any hope of a quick and politically tidy repeal of Obamacare. To urge calm, some Republicans have already made promises that patients won't lose coverage during a transition period away from Obamacare, while Trump himself has promised "insurance for everybody."

People like Johnson will help determine how successful Republicans are and what types of changes are eventually made to the American health care system

Johnson says she left her job in 2015 because of her health issues and is currently receiving long-term disability benefits. Because of the Affordable Care Act, her three children -- ages 21, 17, and 9 -- could stay on her insurance until they are 26.

"It gives me peace as a mother knowing that they'll still be covered while they look for a job that gives insurance," Johnson said.

Calling elected officials and flipping through C-SPAN and CNN was hardly Johnson's typical morning routine prior to Election Day. But when Donald Trump defeated Hillary Clinton, Johnson said, for the first time in her life, she became worried enough to want to do something.

A Republican-turned-Democrat who voted for John McCain in 2008 and Clinton last year, Johnson was surprised to discover that even in a "red state and a red county and a red city," there was a community of people who shared her concerns -- including about the GOP's efforts to repeal Obamacare.

Johnson is constantly checking Facebook, where local activists in the area -- plenty of them brand new to politics like Johnson is -- are eager to spread the word and mobilize. On this Thursday, their next target was a town hall that evening hosted by the Middle Tennessee State University's College Republicans. The event featured GOP Rep. Diane Black, a staunch opponent of the Affordable Care Act.

The Democrats' tea party movement

For years, Democratic Party leaders lamented that their base seemed less motivated than conservatives. Democratic turnout dropped during the off-years and party officials struggled to get voters energized --- something that appears to be changing after Trump's victory.

"All different kinds of people in all parts of the country are spurred into action out of fear of what Trump's government will do to them, their family, their friends and the future of their country," said Jesse Ferguson, a former Clinton aide now working with Democrats to oppose Obamacare repeal. "For many of them, repealing health care is tip of the spear and first of those fears."

These emotionally charged events harken back to the summer of 2009, when constituents across the country flooded the town halls of Democratic lawmakers to oppose Obamacare even before it was signed into law.

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Some of these people have voted for Democrats in the past but have not been politically engaged, while others consider themselves to be independent and have supported both parties.

Many say they are not fully satisfied with the Affordable Care Act and that the law is flawed. But they are alarmed at the idea of outright repeal and deeply disturbed that Republicans don't yet have an alternative to the current health care system.

Democratic lawmakers have been heartened by what they see as signs that their base is waking up. In the coming weeks and months, activists plan to inundate GOP members of Congress with phone calls and visits to their office hours and town halls.

What happens to the parts of Obamacare people like?

April Carroll had no idea that she would be fielding questions from the national media last week.

As president of the MTSU College Republicans, Carroll -- a 20-year-old political science major --- organized Thursday's "Ask Your Reps" event with Black and other local Republican officials. The same event last year drew around 30 to 40 people; this year, a room that seated around 90 was filled to capacity while dozens of protesters gathered outside in the 32-degree cold to express their anger and frustration.

Carroll told CNN that most of the pre-submitted questions this year were about Obamacare -- in particular, how Republicans would replace the sweeping law that covers some 20 million Americans.

And there was a reoccurring theme in the questions that were submitted by MTSU students, she said: "I'm on my parents' insurance 'til I'm 26... When Republicans in Congress do replace Obamacare, is that still going to stay on there?"

Carroll's counterpart on campus is Dalton Slatton, a 19-year-old freshman who is head of the MTSU College Democrats. Slatton was born in Whitwell, Tennessee -- a town that is so small -- "We have two red lights," he quipped -- that when he was born, his parents had to go to a hospital in Chattanooga.

For Slatton, his participation in Thursday night's protest was personal. His parents got health coverage in 2016 through Obamacare. At the time, he said, the small company where his mother worked didn't provide health coverage, while his dad was unemployed at the time, in addition to having had back surgery that would have been considered a pre-existing condition.

Amid all of the recent talk of Obamacare repeal, the Slattons researched how expensive health insurance would be for the family if Obamacare went away. It would likely cost the family around $1,500 to $2,000 a month -- up from the $550 they are paying now.

Could they afford that? "No," Slatton said.

His parents don't vote, Slatton said, but his dad's side of the family is very conservative. Slatton is certain that his dad would have been a Trump voter.

"There's things that can be fixed about Obamacare but my dad does not support repealing it at all," he said. "He believes it is a good program."

Access versus care

Johnson was one of the protesters able to get inside Thursday night's town hall, where security was tight and many were not allowed in.

Seated two rows from the back, she was impatient. As the panelists were asked pre-submitted questions about health care policy, Johnson stubbornly kept her arm raised, prompting the moderator to finally remind her and others of the "ground rules."

"I respect your arm muscles," the moderator said, "but I want to make sure you don't get tired."

The next question to the Republicans officeholders was this: "What are you going to do to make sure that individuals who gained coverage under Obamacare will still have access to affordable health care?"

Johnson blurted out: "Not access -- get health care. Not access -- have health care." This prompted another reminder of the rules.

Johnson never got to ask a question, but several others with serious concerns about Obamacare repeal did

"I have to have coverage to make sure I don't die. There are people now who have cancer that have that coverage, that have to have that coverage to make sure they don't die," said Mike Carlson, a 32-year-old student. "And you want to take away this coverage — and have nothing to replace it with! How can I trust you to do anything that's in our interest at all?"

Jessi Bohon, a 35-year-old high school teacher who lives in Cookeville, Tennessee, was visibly emotional.

"As a Christian, my whole philosophy in life is pull up the unfortunate," Bohon said, a comment that drew verbal affirmation from others in the room. "The individual mandate: that's what it does. The healthy people pull up the sick."

Bohon went on to ask how Congress could be OK with "punishing our sickest people" rather than trying to "fix what's wrong with Obamacare."

Video of Bohon's remarks posted on Twitter was retweeted more than 28,000 times by Sunday.

Johnson told CNN afterward that she was surprised by how outspoken she was during her first town hall.

"I felt so alone prior to the election, you know what I mean? I felt alone in my views, I felt alone in what I thought was important," she said. "I just really felt like I couldn't be quiet. I couldn't stay silent. And I couldn't do nothing."