House Speaker Nancy Pelosi on Friday pushed to rally support for Democrats' latest $3 trillion coronavirus relief bill, even as the White House has threatened to veto the legislation and Republican lawmakers have blasted it as a "parade of absurdities."

The White House, in a formal veto threat overnight, said the bill is packed with “ideological wish lists."

But Pelosi, D-Calif., on Friday morning, penned a letter to all House lawmakers urging “careful consideration” of the latest stimulus package, titled the HEROES Act, which comes up for a showdown vote later in the day.

PELOSI CALLS $3T CORONAVIRUS RELIEF BILL DEMOCRATS' STARTING OFFER AS WHITE HOUSE ISSUES VETO THREAT

“Today, the House will consider The Heroes Act to honor those on the frontlines – our health care, first responders, teachers, transit, food and other essential workers,” Pelosi wrote. “Many of them risked their lives to save lives and now they may lose their jobs.”

Pelosi noted that governors across the country are “planning their budgets,” and could be forced to “cut services and/or raise taxes.”

“The Congress of the United States must honor its responsibility to the American people to lessen the blow of the coronavirus by making the serious investment of The Heroes Act to our state, local, tribal and territorial governments,” she wrote. “The plan that we are voting on today will make a tremendous difference not only in the budgets of the states but in the lives of the American people: their public health, the education of our children, the sanitation so important to defeating the virus, with the support of so many essential workers.”

Pelosi also argued that the legislation includes a “strategic plan to test, trace, treat and isolate” amid coronavirus. The bill adds $75 billion to “ensure every American can access free coronavirus treatment,” and to expand testing and contact tracing.

“As families are devastated by the loss of life, this legislation places money in the pockets of the American people, which is also a stimulus to our economy,” she said, quoting Federal Reserve Chairman Jerome Powell, who said “Additional fiscal support could be costly, but worth it if it helps avoid long-term economic damage and leaves us with a stronger recovery.”

WHAT'S IN THE LATEST STIMULUS BILL?

The new bill introduced this week is more than 1,800 pages long and has a price tag of roughly $3 trillion.

The package includes another $1,200 stimulus payment for each family member in a household, totaling up to $6,000.

The bill allocates nearly $1 trillion to state, local and tribal governments for “honoring our heroes.” The bill also creates a “Heroes Fund,” which provides $200 billion to essential workers who worked during the pandemic as hazard pay.

The bill also extends the Paycheck Protection Program and adds $10 billion in COVID-19 emergency grants.

The bill extends add-on unemployment benefits of $600 payments, in addition to state benefits, through January 2021, creates a special enrollment period in Affordable Care Act exchanges for the uninsured, provides $175 billion for families to pay their mortgages and rent, and increased maximum SNAP benefits, which are currently $768 a month, by 15 percent.

But on Thursday, the White House issued an official veto threat, accusing Democrats of wanting to pass "long-standing partisan and ideological wish lists" rather than addressing the nation's public health and economic challenges.

MCCONNELL PREDICTS 'HIGH LIKELIHOOD' OF NEW STIMULUS BILL, DISMISSES DEM PROPOSAL AS 'PARADE OF ABSURDITIES'

The White House chided Democrats for making certain undocumented immigrants eligible for the second round of $1,200 direct payments, for including a $25 billion "bailout" for the U.S. Postal Service and for funding vote-by-mail and same-day registration priorities.

Meanwhile, Republicans have blasted the legislation, with Senate Majority Leader Mitch McConnell, R-Ky., calling the $3 trillion House proposal “unsalvageable.”

“The president and Senate Republicans are going to be in the same place,” McConnell said on “Special Report” Thursday. “We will let you know when we think the time is right to begin to move again.”

While prior rounds of stimulus legislation have gained bipartisan support, Republicans largely have been cool to a fifth round of coronavirus relief legislation -- arguing it's time to pause after nearly $3 trillion already has been borrowed to pay for the aid to small businesses, laid-off workers and Americans stuck at home.

McConnell said he thinks “there’s a high likelihood we’ll do another bill,” but said that the House proposal is a “liberal wish list” and “a parade of absurdities that can hardly be taken seriously.”

But Pelosi said Thursday that this $3 trillion package is just the starting off point for House Democrats, and that they are open to changes.

"We're putting our offer on the table, we're open to negotiation," Pelosi said Thursday."This is really quite an exciting time for us because we have a monumental need for our country at this sad time."

McConnell emphasized, though, that any further coronavirus aid bill would have to include liability protection for businesses and other organizations that resume operations amid the pandemic.

"Our red line is going to be liability protections for those who are brave enough to begin to open up the economy again in the wake of the trial lawyers who are descending already on hospitals and doctors and businesses as of about a week and a half ago," McConnell said.

"And people have to be brave enough to begin to engage in economic activity," he added. "How about the presidents of universities? Are they willing to open up for the fall or are we going to have another period of time where not only K through 12 students, but potentially college students are still at home? All of those questions need to be answered by the fall."

Fox News' Marisa Schultz and Victor Garcia and The Associated Press contributed to this report.