The 2020 edition of the Conservative Political Action Conference in Oxon Hill, Md., in February offered a theme-park version of what was to be President Trump’s re-election message: Under the banner of “America vs. Socialism,” the convention featured anti-Marx branded popcorn, an RV emblazed with the words “Socialism Takes Capitalism Creates” and a children’s book promoting personal freedom and private-property rights.

Speeches included tirades against big government and “Medicare for all.”

“The virus is not going to sink the American economy,” the president’s chief economic adviser, Larry Kudlow, told a packed auditorium. “What is or could sink the American economy is the socialism coming from our friends on the other side of the aisle.” Mr. Trump, the keynote speaker, proclaimed, “We are defeating the radical, socialist Democrats” who “want total control.”

Four weeks later, with the coronavirus sinking the American economy, the federal government was preparing to cut $1,200 checks to tens of millions of citizens, part of a $2 trillion economic stabilization package that was also providing businesses with no-interest loans — likely to be partly forgiven — to pay their employees while they are shuttered. The Trump administration was issuing guidance for Americans to stay inside their homes while weighing a New Deal-style infrastructure program to create jobs.

And the CPAC message seemed a relic from a distant time.

Such is life for the political warriors of the Covid-19 campaign, where, in this pre-peak stage of the crisis, the national political debate is inside out and upside down, sending both sides of the national divide scurrying to figure out where the new political and ideological lines will settle come the fall.

As Republicans prepare for a re-election battle almost certain to hinge on perceptions of the Trump administration’s readiness and efficiency in performing its most solemn duty — to protect American lives — the decades-old debate over government’s role in American life has entered an unfamiliar phase of discombobulation. A president who leads a movement that was galvanized by Ronald Reagan’s motto that the four most terrifying words from the government were “I’m here to help” is now responsible for the largest federal disaster response since the Great Depression.

“The era of limited-government, country-club Republicanism is over,” said Stephen K. Bannon, an ideological architect of Mr. Trump’s 2016 victory.

At the same time, lingering conservative distrust of government and “experts,” combined with a red-and-blue fissure over the severity of the crisis, have surfaced dystopian national divisions: between those taking social-distancing measures seriously and those who view them as resulting from government overreach, between those who would support a prolonged economic shutdown and those who would be willing to trade additional casualties for a faster return to normalcy. “That,” said Matt Schlapp, chairman of the American Conservative Union, “is one of the questions our politics will solve in November.”

In the middle of it all is the president, whose operatic inconsistency about his administration’s role was apparent on Saturday when he predicted “a lot of death” but raised the possibility of relaxed social-distancing guidelines for Easter services.

It is so early in the crisis that both sides are navigating public opinion day to day, uncertain whether the fault lines have been truly scrambled or will re-emerge only hardened once the crisis abates, whenever that is.

“We don’t know what it’s going to look like on the other side of this in terms of people’s attitudes — whether it’s going to have short-term effects or long-term effects,” said Anita Dunn, a senior adviser to former Vice President Joseph R. Biden Jr., the likely Democratic presidential nominee.

The sudden, unprecedented nature of the election cycle has made it impossible to strategize too far ahead: The party conventions, where nominees make their strongest cases, are in doubt; traditional retail politicking, necessary for exciting base voters and winning over converts, is impossible, and voting is facing a potential shift toward more mail-only balloting than ever before in a presidential election.

With the death count mounting last week, the two sides were sparring over whether Mr. Trump’s early declarations that the virus was contained had cost lives.

“He has some great vulnerabilities no matter how many proposals he puts out, and the single greatest one of them is the month of February,” Ms. Dunn said. “The number of people who are sick is significantly greater than it needed to be because this administration didn’t act when it could have — and that is not an issue that is going to go away.”

For their part, Trump campaign aides were trying to go on offense, painting Mr. Biden and the Democrats as working to undermine Mr. Trump as he seeks to lead the country through the crisis as a “wartime president.”

“In January, while the Democrats were entirely focused on impeachment, President Trump took the critical step of restricting travel from China in response to the coronavirus,” the campaign said in a statement. It criticized Mr. Biden for calling Mr. Trump’s response “xenophobic” and pointed to polls showing approval of Mr. Trump’s handling of the pandemic. (An ABC News/Ipsos poll on Friday showed his support dipping from an earlier uptick.)

Beyond the back and forth is the question that has rested at the heart of American politics since the New Deal: What is the federal government’s appropriate place in managing public welfare and private behavior?

Democrats view the crisis as vindicating their long-held belief in “the importance of government and the functions that only a government can do,” as Ms. Dunn put it.

Conservatives ascended over the last decade with the anti-government, institutions-skeptical sentiment of the Tea Party, which was itself partly fueled by anger over the bank bailouts and the stimulus measures that followed the 2008 financial crisis.

Mr. Trump took the White House embracing the movement’s resentment of elites and “experts,” and his administration moved quickly to cut back agencies — including a Centers for Disease Control and Prevention program built to detect and manage potential viral outbreaks — as it vowed to end the Affordable Care Act.

“Now we’re in a crisis where big government is the only thing that can save us, and elites — a combination of these two things that Republicans say they hate,” said Stuart Stevens, a Republican strategist for the George W. Bush and Mitt Romney campaigns who has soured on his party in the Trump era.

So far, Mr. Trump, politically limber to begin with, has sought to have his $2 trillion federal response and eat it, too.

He has shared billing on the front of the mailing for “The President’s Coronavirus Guidelines for America” with the Centers for Disease Control, an agency some of his supporters view as part of the so-called deep state. And he approved the C.D.C. recommendation that all Americans wear masks.

Yet he said he would not wear a mask himself. He has praised the government’s lead infectious-disease official, Dr. Anthony Fauci, but dismissed Dr. Fauci’s call for a national stay-at-home order, as some Republican governors resist going along with the C.D.C. guidance.

In a sign of the ideological fogginess of the moment, the Trump campaign on Friday argued in an email that Mr. Biden’s plan to add a government-run option to the Affordable Care Act “would end Obamacare as we know it,” as Mr. Trump continues to back a lawsuit seeking to do just that.

Guy Cecil, chairman of the major Democratic super PAC Priorities USA, said the administration’s anti-Obamacare position would prove politically punishing as the pandemic wore on.

“The fact that the administration is still seeking to overturn the Affordable Care Act at a time when more people are being thrown off their health care is only going to become more important,” he said.

It was only a few weeks ago that centrist Democrats were openly fretting that Senator Bernie Sanders’s Medicare for all plan and Andrew Yang’s call for a universal basic income would hurt the entire party with swing voters by feeding the Republicans’ “socialism” theme.

Now, with the swift bipartisan passage of the $2 trillion stimulus, perhaps only the first of its kind, those fears are subsiding.

“It makes it harder to label your opponent a socialist,” said Howard Wolfson, a top strategist for former Mayor Michael R. Bloomberg of New York, who ended his presidential bid last month.

The moment is not without irony for Mr. Sanders, whose chances to win the nomination have faded as his signature proposals have appeared to gain greater acceptance. A Morning Consult/Politico poll released last week found that Medicare for all had support from 55 percent of registered voters, up nine percentage points from mid-February.

“I’d love to see you tell me that you can’t campaign on free treatment now,” said Mr. Sanders’s campaign manager, Faiz Shakir. “Because all of our fates depend on everyone being tested and treated.”

With a “Yangwasright” hashtag trending on Twitter, a Marquette University Law School poll of Wisconsin voters found nearly 80 percent generally approved of the government’s direct payments to individuals.

Mr. Bannon, who left the Trump administration in 2017, saw evidence of a national coming together for measures, like a $15 federal minimum wage, to help “the heroes of this catastrophe” — whom he identified as “the truck drivers, the kids at the Amazon plants, police, doctors and nurses.”

He predicted a pandemic-born political realignment in step with his own brand of “economic nationalism,” in which shared resentment over income inequality, corporate greed and global trade policies that gave China so much economic influence in the United States would create a new political coalition drawn from Sanders supporters, working-class Democrats and Republicans.

“What we want is a better deal for the little guy — trade barrier protections, high wages and also entrepreneurialism, not corporate capitalism,” he said.

Republicans close to the White House argued that the party’s primary tenets were unshakable, even in this crisis.

For instance, where Mr. Trump has been hesitant in using the Defense Production Act to compel American factories to produce medical supplies, “Joe Biden and Democrats call for compulsion, which is markedly different,” said Tim Murtaugh, the Trump campaign communications director.

Mr. Trump has likened government mandates for manufacturers to nationalization of industry, a line his supporters presumably would not want him to cross. Parts of his political base are chafing at government moves to control social interactions and shutter businesses to fight the virus.

With that in mind, Mr. Schlapp, the chairman of the American Conservative Union, which runs CPAC, described the huge aid package as restitution, not socialism.

“The conservative principle is when government takes your property and economic rights, they are obligated to come up with a financial settlement,” said Mr. Schlapp, whose wife, Mercedes Schlapp, is a Trump campaign adviser.

Conservatives, he said, are less deferential to government than their liberal counterparts and are not likely to put up with it for long, presaging a potentially intense election-year conflict between left and right over when to end social distancing measures.

“Eventually, we have to ask ourselves, what’s the appropriate level of risk to open it back up,” Mr. Schlapp said. “It will be a showdown, and I think that will tell us a lot about our country.”