Republicans are facing major head winds in their bid to maintain control of the Senate, a troubling outlook for the party roiled by news of President Trump and three GOP senators contracting the coronavirus four weeks before the election.

In a tumultuous year marked by a pandemic that has killed nearly 210,000 Americans and civil unrest, Republicans saw the fight over a Supreme Court vacancy as a chance to boost their political fortunes. Court fights typically rally the GOP base, and Senate Majority Leader Mitch McConnell (R-Ky.) encouraged Trump to move quickly to select a conservative nominee to galvanize voters.

But the GOP’s predicted Supreme Court bump has yet to materialize. And the party is now facing down a new level of uncertainty as the coronavirus spreads in GOP circles in Washington, with Sens. Thom Tillis (N.C.), Mike Lee (Utah) and Ron Johnson (Wis.) testing positive.

A week after President Trump tapped Amy Coney Barrett as Supreme Court nominee, he and several attendees at the event have tested positive for coronavirus. (The Washington Post)

Rather than serving as a major boost to their campaigns, Trump’s Supreme Court announcement at the White House on Sept. 26 appears to have served as a superspreader event, with a couple dozen infections connected to that day. That is certain to bring Trump’s response to the pandemic to the forefront of voter’s minds in the lead-up to Nov. 3 — the last thing Republicans wanted.

“I think it’s 50-50,” McConnell told conservative talk radio host Hugh Hewitt on Friday when asked whether the GOP will hold the Senate. “We always knew this was going to be challenging.”

“We have close, hard-fought races all over the country,” McConnell said, adding that “the Democrats are competing with us in Kansas and Georgia and even South Carolina.”

That concern grew deeper as Democratic challengers began unveiling eye-popping fundraising totals, revealing that anti-Trump liberal energy has only grown stronger as sides gird for a Supreme Court fight.

In North Carolina, Cal Cunningham (D), running in what many consider the tipping-point race, raised more than $28 million, a three-month haul that represents more than double the amount that Tillis, the GOP incumbent, raised in the previous 5½ years.

It remained to be seen how badly Cunningham has damaged his chances with his acknowledgment Friday of intimate texts with a woman who is not his wife, a self-inflicted blow that could ensure the GOP holds the seat.

Overall, Democratic candidates MJ Hegar in Texas and Raphael Warnock in Georgia reported raising $13.5 million and $12.5 million, providing enough funds to turn races where Republicans had distinct advantages into more competitive battles in the final weeks. And GOP strategists were bracing for a potentially record-setting haul from Jaime Harrison, the South Carolina Democrat who has forced Republicans to divert about $10 million to defend Sen. Lindsey O. Graham in a state Trump won by more than 14 percentage points four years ago.

“We have grassroots momentum behind us, we hold an advantage on the issues that matter most to voters, and we continue to have a strong path to winning back the majority,” Senate Minority Leader Charles E. Schumer (D-N.Y.) said in a statement to The Washington Post. “The Republicans’ mismanaged response to this pandemic and the rush to confirm a Supreme Court justice . . . has underscored just how important it is to flip the Senate.”

Republicans have divided their map into two tiers of four races. The most vulnerable incumbents in Democratic-leaning or swing states are Tillis and Sens. Susan Collins (Maine), Cory Gardner (Colo.) and Martha McSally (Ariz.).

The next tier is what the GOP has privately referred to as its firewall for holding the majority, races in GOP-leaning states that they must win. The incumbents are Sens. Joni Ernst (Iowa), Steve Daines (Mont.), David Perdue (Ga.) and Kelly Loeffler (Ga.).

Republicans and Democrats expect GOP candidate Tommy Tuberville to oust Sen. Doug Jones (D) in strongly Republican Alabama, giving the GOP one more seat. Republicans can lose all four of their most vulnerable senators as long as they maintain their firewall and Trump wins a second term. Should Joe Biden win, they have to hold on to one of those front-line seats, as well as their second tier.

Yet there are fresh signs that even the GOP’s firewall is cracking. In Georgia, a recent Quinnipiac University poll shows Warnock ahead, with the special election turning into a nail-biter amid Republican infighting. Rep. Douglas A. Collins (R-Ga.) has waged a vicious campaign against Loeffler, siphoning off GOP support she needs to defeat the little-known Black Baptist pastor from Atlanta.

Perdue’s race is too close for GOP comfort, with Democrat Jon Ossoff competitive with the Republican incumbent whose deep ties to the Atlanta suburbs have long boosted him. The races have led some Republicans to joke privately about the possibility of celebrating the holidays in the Peach State, amid the possibility of runoffs in January.

To win, a candidate must get a majority of the vote.

In South Carolina, Graham is tied with Harrison, according to a Post analysis of three polls taken there last month. In the traditionally conservative state, Graham, the three-term senator who won his last race by 17 percentage points, is getting so desperate for cash that he has taken to begging Fox News viewers to donate to his race on live national television.

“I’m getting overwhelmed,” he told prime-time host Sean Hannity late last month. Then, he turned to Hannity’s viewers, adding: “Help me! They’re killing me money-wise. Help me. You did last week. Help me again.”

The shape of the races is evident based on where outside conservative groups, aligned with McConnell, are spending their resources to defend the Republican majority. In the final five weeks of the campaign, those groups have devoted $110 million to nine states where Republicans hold the seat, according to estimates from the Democratic Senatorial Campaign Committee.

Those groups are on offense against just one Democratic seat, that of Sen. Gary Peters (Mich.), whose race against a well-funded Republican, John James, has grown increasingly close despite Biden’s continued strength in a state that Trump narrowly won in 2016. Some allies of Peters have sent warnings to Democratic leaders that if they do not shore up what should be an easy victory, they could fall shy of the majority.

Republicans also argue that there is plenty of time to steady the ship. GOP operatives are still predicting a Supreme Court boost once the confirmation hearings begin Oct. 12 for Judge Amy Coney Barrett, Trump’s choice to replace Justice Ruth Bader Ginsburg after her death last month.

But in debates Saturday night, Graham and Ernst found themselves on the defensive over the coronavirus, the government response and some of their past comments.

Graham, the chairman of the Senate Judiciary Committee, sought to focus on his concerted effort to confirm Barrett. But Harrison, who brought his own plexiglass divider as he shared the stage with Graham, criticized the response to the disease.

“We failed to act,” Harrison said. “The Senate failed to act. The White House failed to act. The governors failed to act. We need leaders who are going to step up and act.”

Graham called the virus “serious” but said that “we have to move on as a nation.”

In Iowa, Democratic challenger Theresa Greenfield called on Ernst to apologize for her comments last month echoing a conspiracy theory that the death count has been overcounted and arguing that health-care providers are reimbursed at a higher rate when deaths are linked to covid-19.

“I have apologized to our health-care workers and I will apologize again tonight,” Ernst said. “I am so sorry that my words may have offended you. I know that you are tremendous workers. You are essential workers.”

Even before Trump’s coronavirus diagnosis, Republicans acknowledged that his combative debate performance last week did not help them. His refusal to condemn white supremacy dumbfounded many GOP lawmakers, who also thought he lost a chance to cast Biden and the Democrats as beholden to what they call the “radical left.”

“You know we didn’t get great clarity from the debate last night about the differences in vision of the future of this country,” said Sen. Todd C. Young (R-Ind.), who’s leading the GOP’s campaign arm. “And I think that was unfortunate.”

In clear sign of GOP nervousness, five Republicans on the ballot this fall cast symbolic votes to block the Trump administration from continuing its legal fight to overturn the Affordable Care Act and its protections for preexisting conditions. Collins, Gardner, Ernst, McSally and Sen. Dan Sullivan (R-Alaska) joined Democrats last week in backing the measure, which fell short of the 60-vote threshold.

Democrats, meanwhile, point to evidence of a jolt of energy on their side. ActBlue, the liberal online donation site, has raised nearly $500 million for Democratic candidates since Ginsburg’s death, and Senate candidates have seen a rush of donations as well.

Crooked Media, a liberal group founded by alumni of the Obama White House, set up a “Get Mitch” fund for Senate candidates in the summer of 2019 that had raised only $3.5 million before the evening of Sept. 18. In the next 12 days, after Ginsburg’s death, the fund hauled in more than $23 million, disbursing between $1.7 million and $1.9 million to 13 Senate candidates, according to Shaniqua McClendon, political director for Crooked Media.

A pair of Democratic challengers, Mark Kelly in Arizona and Amy McGrath in Kentucky, have already raised so much money that McClendon turned off the online donor drive for their campaigns, to steer money into campaigns that need the cash more. They expect to turn Harrison’s campaign off for donors soon.

“We want it to be impactful dollars,” McClendon said. “They don’t need the money. Other people do. So let’s get it to them.”