Senate Majority Leader Mitch McConnell, a Republican from Kentucky, left, speaks as U.S. House Minority Leader Kevin McCarthy, a Republican from California, right, and U.S. President Donald Trump listen before the H.R. 748, Coronavirus Aid, Relief, and Economic Security (CARES) Act, is signed in the Oval Office of the White House in Washington, D.C., U.S., on Friday, March 27, 2020.

Erin Schaff | Bloomberg | Getty Images

Senate Republicans will delay the release of their coronavirus relief plan until next week, Senate Majority Leader Mitch McConnell said Thursday, assuring Congress will miss a deadline to extend a key unemployment insurance boost. 

“The [Trump] administration has requested additional time to review the fine details, but we will be laying down the proposal early next week,” the Kentucky Republican said. “We have an agreement in principle on the shape of the package.”

The GOP had hoped to unveil legislation as soon as Thursday, which would have kickstarted talks with Democrats on a bill that could pass both chambers of Congress. But Senate Republicans have not been able to nail down final details with the White House even as millions of jobless Americans move closer to a financial cliff. 

States will stop paying out out the $600 per week enhanced unemployment benefit passed in March at the end of this week. The policy formally expires at the end of July. 

Earlier Thursday, the top congressional Democrats hammered into GOP leaders for delays in releasing a plan on a day the U.S. reached the grisly benchmark of 4 million Covid-19 cases. 

“The Republican disarray and dithering has serious potentially deadly consequences for tens of millions of Americans,” Senate Minority Leader Chuck Schumer, D-N.Y., said at a news conference with House Speaker Nancy Pelosi, D-Calif.

READ ALSO  SE: OMERS Would Love to Invest More in Canada, CEO Says

This story is developing. Please check back for updates. 

Subscribe to CNBC on YouTube.