Congressional Democrats, angered by the Trump administration's refusal to begin the formal transition process to President-elect Joe Biden, are demanding a briefing on the matter from the head of the General Services Administration on Tuesday.

Updated at 6:15 p.m. ET

The United States has had 77 Treasury secretaries in the last 231 years. So far, they've all been men.

That's about to change.

President-elect Joe Biden plans to nominate former Federal Reserve Chair Janet Yellen to head the Treasury Department, a source close to the transition told NPR on Monday

If confirmed, Yellen would play a leading role in shaping economic policy as the United States continues to dig its way out of the deep hole caused by the coronavirus pandemic.

Updated at 3:56 p.m. ET

President-elect Joe Biden has named six leaders of his foreign policy and national security teams, showing a continued push for historic firsts in his administration.

He's also set to name former Federal Reserve Chair Janet Yellen as his treasury secretary, NPR's Franco Ordoñez reports. Yellen, 74, was the first-ever female Fed chair and would be the first-ever female head of the U.S. Treasury.

Updated at 8:21 p.m. ET

The Michigan Board of State Canvassers voted Monday to certify the state's election results after weeks of attempts by President Trump, the outgoing Republican nominee, to overturn his opponent's victory. Three members voted in favor of certification, and one abstained.

It has become the battle cry of public health officials around the world: "Wear a mask to slow the spread." Friday, the U.S. Centers for Disease Control and Prevention released new evidence supporting this advice.

Researchers analyzed coronavirus infection rates in Kansas following a statewide mask mandate. They found that counties that chose to enforce the mandate saw their cases decrease. Counties that chose to opt out saw their cases continue to rise.