Secretary of State Antony Blinken, reporting for work at the State Department, told the agency's 70,000 employees around the world, "I will have your back."

"It’s a new day for America. It's a new day for the world," Blinken said in remarks shortly after entering the building, calling his return "like a homecoming."

Blinken recalled how his career began at the State Department 28 years ago as a special assistant. He last served in the department four years ago as its deputy secretary in the Obama administration and acknowledged the changes the agency and the world have undergone since.

"To date, the pandemic has claimed the lives of five State Department Americans and 42 locally employed staff around the world," Blinken said. "And outside our doors, our government buildings are surrounded by new barricades. We’ve never been in a moment quite like this before."

He went on to pledge to be an inclusive, transparent and morale-building boss, arguing, "We at State have a role to play in all of this."

Blinken also vowed to invest in building a diverse and inclusive agency that is "truly representative of the American people."

He said "the world is watching us intently right now" to see "if we can heal our nation," but, in a nod to the appeal of the Trump administration's more isolationist approach, Blinken noted that the department must work first for the American people, saying the public wants to see "that our foreign policy is about them and their lives."

"We will do right by them," he said. "Now let’s get to work."

-ABC News Conor Finnegan

With the second impeachment trial of former President Donald Trump slated to formally begin in two weeks, Sen. Rand Paul, R-Ky., forced a procedural vote on the constitutionality of trying a former president on Tuesday and was met with the support of 45 Republicans -- just three weeks after the Capitol, including the Senate chamber, was invaded. Though anything could happen at trial, the vote signals Democrats will not have the numbers to convict Trump and bar him from holding future federal office.

The idea behind delaying Trump's trial to Feb. 9, an agreement reached by party leaders, was reached so that the Senate could work on Biden's Cabinet confirmations and COVID-19 relief while the House impeachment managers and Trump's defense team prepare.

On the Cabinet front, Biden meets his one-week anniversary in office with four Cabinet officials confirmed -- lagging behind other administrations in recent history. On Wednesday, confirmation hearings will be held for Jennifer Granholm for the energy secretary, Linda Thomas-Greenfield at U.N. ambassador, and Denis McDonough to lead the Department of Veterans Affairs.

The president on Wednesday will turn his attention to the climate crisis with a suite of new executive actions -- making tackling climate change a priority across the federal government.

Biden, who has already revoked a permit for the controversial Keystone XL pipeline project and moved to rejoin the Paris Agreement on climate, is scheduled to deliver afternoon remarks and sign executive actions at 1:30 p.m., fulfilling campaign promises such as freezing new oil and gas leasing on federal land and kicking off his ambitious agenda to reduce greenhouse gas emissions.

White House press secretary Jen Psaki will also hold a press briefing with the nation's first ever climate envoy, former Secretary of State John Kerry, and Biden's national climate advisor, Gina McCarthy, around 12:15 p.m.

Kicking off what's expected to happen three times a week moving forward, White House COVID-19 response team and other public health officials will hold a virtual, public briefing on the pandemic at 11 a.m. with participants including Biden's chief medical adviser Dr. Anthony Fauci, COVID-19 response coordinator Jeff Zients and Centers for Disease Control and Prevention Director Dr. Rochelle Walensky.

Marking one week as president, Biden will turn his attention to the climate crisis with a suite of new executive actions Wednesday.

The president, who has already revoked a permit for the controversial Keystone XL pipeline project and moved to reinstate the country to the Paris Agreement, will deliver remarks and sign executive actions on tackling climate change, creating jobs and restoring scientific integrity in the White House State Dining Room on Tuesday afternoon.

White House press secretary Jen Psaki will also hold a press briefing with Biden's climate envoy, former Secretary of State John Kerry, and Biden's national climate adviser, Gina McCarthy.

-ABC News' Sarah Kolinovsky

Sen. Patrick Leahy, D-Vt., has been released from the hospital Tuesday night after being taken "out of an abundance of caution" earlier in the day. The 80-year-old was taken to a local hospital after he told staffers at the Capitol he was feeling sick, a spokesperson said Tuesday evening.

Leahy is currently the most senior Senate Democrat -- the "president pro tempore" -- and as such is presiding over Donald Trump's impeachment trial.

"The Capitol Physician suggested that Senator Leahy go to George Washington University Hospital this evening for observation, out of an abundance of caution," David Carle, spokesman for Leahy, said in a statement. "After getting test results back, and after a thorough examination, Senator Leahy now is home. He looks forward to getting back to work."

There was no mention of his symptoms, or whether he was tested for COVID-19.

Leahy has served in the Senate since 1975.

-ABC News' Trish Turner and Allie Pecorin