Analysis by Gregory Krieg and David Wright, CNN

(CNN) -- There is no more durable feature of Democratic politics than the ritual agonizing over the party's inability to organize itself around a coherent message.

In 2018, the most prevalent argument among liberal pundits turns on whether it's a better electoral strategy to target President Donald Trump and his administration or bear down on core economic issues.

But the reality, as we've seen throughout the campaign, is that both are happening. The challenge for party leadership and individual candidates now is more delicate, as they try to tie the two together -- and get voters to pay attention.

Even within that tricky new paradigm, there is a clear consensus around at least one matter: health care. In speeches, debates and ads, Democrats from across the party's ideological spectrum are describing efforts to defend and expand coverage and care as a moral imperative.

From the rumored 2020 presidential challengers in the Senate to midterm candidates up and down the ballot, in both red and blue states and districts, the future of health care in America is shaping up as perhaps the central policy concern of 2018. The contours of the candidates' messages might vary and, for many, the particulars of the path forward -- how far, how fast -- remain an open question. But there is little question, for Democrats in this cycle, which way is up.

Capitol Hill, despite being home to a pair of Republican majorities, has become a stage for Democrats who, in less than two years, have rolled out at least five significant proposals for big ticket expansions of government-backed health care. That the legislation is dead on arrival in Trump's Washington is beside the point. These are statements of intent and appeals to current and future voters.

On the trail this year, candidates have swung at the issue from all angles. A scan of ads from congressional hopefuls reveals a diverse suite of tactics buttressed by a clear strategic decision to hammer Republicans over their efforts to gut Obamacare and either cut or complicate funding for programs like Medicaid.

In California's 48th District, Harley Rouda, a businessman who registered as a Democrat only after the 2016 election, now has the support of the Democratic Congressional Campaign Committee; Indivisible, the grass-roots liberal group; and the union activists from the California Nurses Association/National Nurses United. It's an unusual combination -- one that wouldn't have been possible, in all likelihood, without his early support for single-payer health care.

"When I talk about 'Medicare for all,' I can provide the economic rationale and logic, the foundation as to why it makes good business sense," Rouda said last month, explaining how his pitch will play in wealthy Orange County, "and be credible in that since I've had the privilege of managing companies of almost 10,000 people."

Rouda's assessment of the national political scene is similar to the one informing radical progressives, while jibing with polls that show health care at or near the top of voters' minds.

"The country is certainly coming around to how important the ACA has been," he said, citing the backlash to the GOP's failed attempts to repeal the Affordable Care Act in 2017 and subsequent efforts to undermine it. "When people realized what the impact would be if it was terminated, they actually stopped and paused and said, 'Wait a minute, maybe this is better than we thought?' And the fact is, it hasn't gone far enough."

That push -- further! -- is a recurring theme in Democratic campaign communications around the country, even among candidates fighting to flip their desired seats in red or swing states and districts. Angie Craig, in Minnesota's 2nd Congressional District, wants "immediate fixes to the Affordable Care Act, and work toward universal health coverage." Arizona's Democratic Rep. Kyrsten Sinema, who's running to replace the retiring GOP Sen. Jeff Flake, said in a recent ad that she wanted to "fix what's broken in the system," rather than blow it up.

Others are even more direct -- and ambitious.

In Nevada's 4th District, currently held by Democrats, Amy Vilela called her daughter Shalynne, who died in 2015 after her medical treatment was compromised -- as Vilela alleges -- by insurance issues, "a victim of our for-profit health care system."

"I know what it's like to have to pay the ultimate price because we have politicians that are not interested in putting the needs of the people first," Vilela says in an ad. Her primary opponent, Steven Horsford, asks on his website, "Do you have a health care story? Share it with Steven here." He then spells out a three-step plan to take on "greedy pharmaceutical companies" and drive down prescription drug prices.

Meanwhile, the Democratic Congressional Campaign Committee hit GOP Rep. Will Hurd, whose seat in Texas' 23rd District could be the state's most hotly contested, with an ominous, 60-second radio spot that asks at one point "what Hurd might do next to your health care?" (Hurd, noting the danger, was one of the few Republicans who voted against the House Obamacare replacement bill.)

"Your congressman, Will Hurd, hasn't stopped trying to repeal your health care," the narrator says, as if to remind voters of the anger they felt toward the GOP majority in the midst of the Obamacare fight and, later on, when Republicans voted to repeal the individual mandate as part of their tax cut package.

In Kentucky's 6th District, Amy McGrath began an ad by explaining that her decision to "retire from the Marines" and enter the race was due, in part, to incumbent Republican "Andy Barr, Mitch McConnell's handpicked congressman, saying he would vote 'enthusiastically' to take health care away from over a quarter million Kentuckians."

McGrath won her primary last week and is slated for a face-off with Barr in November.

In Pennsylvania, Conor Lamb talked about "union rights" and taking action to strengthen Obamacare and its insurance markets on his way to victory in a March special election for the state's 18th Congressional District.

"Paul Ryan will use the term 'entitlement reform' to talk about Social Security and Medicare as if it's undeserved or it's some form of welfare," he said in an ad. "But it's not any of those things. People paid for it. They worked hard for it and they expect us to keep our promises to them."

It's not the way a liberal candidate in the Northeast or on the West Coast might have put it, but for a party that has, for decades, bent over backward to reject the idea it's anything less than fiscally upright, that kind of language from a red district Democrat can be bracing. Lamb, who was tapped by the state party ahead of the special election and ultimately ran unopposed in his new district's 2018 primary, wasn't pushed left by an insurgent candidate or activist uproar. He got there on his own -- and he's still hammering away.

"Republicans in Congress spent the past year trying to take health insurance away from people with no plan to replace it," it says on his website, which ties coming rate hikes to "a failure of leadership" by the GOP.

For fellow Democrats plotting a similar route, from the deepest of blue districts to once-solid Republican redoubts like Lamb's, the power of that message could make or break their drive to wrest back power in Washington and beyond.