WASHINGTON-Speaker of the House of Representatives Nancy Pelosi announced on Wednesday that paid family leave and sick leave are back in the large-scale social safety net spending plan, but their inclusion in the final draft depends on the support of key centrist Senator Joe Manchin.

In a letter from a dear colleague, Pelosi said: “I have asked the Fundraising Committee to include its paid family and sick leave legislation in this morning’s hearing.” “Chairman Richie Neal and committee staff have long been Committed to this priority and well prepared."

Two sources familiar with the matter told NBC News that the proposal would include four weeks of paid vacation. The source asked to discuss the negotiations anonymously.

In response to the announcement, Manchin said that he still opposed the proposal of paid leave.

"This is a challenge, a very big challenge. They know how I feel about it," he told reporters.

Congress is scrambling to reach an agreement on the core of President Joe Biden's legislative agenda.

When Manchin raised an objection last week, the proposal was removed from the package. He told reporters at the time that he believed that spending measures called the settlement bill should not be used to pass important policy proposals such as paid leave.

He called on the House of Representatives to vote on the infrastructure bill first, which would allocate $555 billion for roads and bridges and other projects, and postpone the vote on the social safety net part (known as the "Rebuild Better Plan"), but he admitted on Tuesday. It is unlikely to happen.

"We will accomplish something. But I still believe in my heart, because of the unknown we have now, we should wait," he said. "We will not wait. The ship has already sailed. I understand this."

Teaganne Finn is a political reporter for NBC News.

Ali Vitali is a political reporter for NBC News in Washington.

Sahil Kapur is a national political reporter for NBC News.