Treasury secretary Janet Yellen, in one of her final major acts in office, warned Congress late Friday that the Treasury will need to begin "extraordinary measures" on Tuesday to avoid hitting the debt limit.

The breach of the debt ceiling officially starts the clock on how long Trump and Congress will have to act to avoid a financially catastrophic default.

Janet L. Yellen, the outgoing Treasury secretary, urged lawmakers to raise the debt limit and protect the full faith and credit of the United States.