Good morning and welcome to Fox News First. Here's what you need to know as you start your Monday ...

Trump defense team gets last-minute reinforcements as Senate impeachment trial is set to begin
After an opening salvo of back-and-forth arguments from President Trump's attorneys and Democrats' impeachment managers on Monday, Senate impeachment trial proceedings are set to begin at 1 p.m. ET on Tuesday with the expectation they will stretch well into the night on Capitol Hill -- even as key procedural questions, including the timeline for debate and whether additional witnesses will testify, remain undecided and hotly contentious.

In a surprise move Monday night, a group of high-profile House Republicans announced that they would formally join the president's legal team, including Reps. Doug Collins, Mike Johnson, Jim Jordan, Debbie Lesko, Mark Meadows, John Ratcliffe, Elise Stefanik and Lee Zeldin. The last-minute show of force underscored the fluid nature of the Senate trial, which is also set to feature full-throated arguments against impeachment from constitutional scholar Alan Dershowitz and Bill Clinton independent counsel Ken Starr.

Senate Majority Leader Mitch McConnell revealed Monday that he wanted a condensed, two-day calendar for each side to give opening statements, at 12 hours per day. After the four days of opening arguments, senators would be allowed up to 16 hours for written questions to the prosecution and defense, followed by four hours of debate. Only then would there be votes on calling other witnesses, likely next week. Much of Tuesday's proceedings will focus on debate over McConnell's proposed resolution for the parameters for the impeachment trial. Click here for more on our top story

Stay with Fox News for complete live team coverage of President Trump's impeachment trial on all platforms.

Other developments in Trump's impeachment:
- Giuliani 'heartbroken' by Lev Parnas' 'stupid lies,' says he's trying to avoid jail
- Alan Dershowitz: Trump impeachment is a 'motion-to-dismiss' case
- Jenna Ellis: Here are four legal problems House Democrats have to face

Swedish environmental activist Greta Thunberg takes her seat prior to the opening session of the World Economic Forum in Davos, Switzerland. (AP Photo/Markus Schreiber)

Trump, climate activist Greta Thunberg set to cross paths at World Economic Forum conference in Davos
The World Economic Forum [WEF] meeting in Switzerland opened Tuesday, and it could play host to a potential round two of the public fight between President Trump and teen climate activist Greta Thunberg.

Following tensions at last fall’s United Nations General Assembly meeting in New York – which included icy glares toward the president by Thunberg and mocking tweets by Trump – the two are expected to cross paths once again in Davos with climate change and its effects on the global economy being major discussion points of the summit.

WEF founder Klaus Schwab said he welcomed both Trump and Thunberg at the summit, calling it “reassuring” and adding that both were set to speak Tuesday on the meeting’s opening day. Click here for more.

China coronavirus claims 4th victim, screening of travelers heightened
A fourth person has died in an outbreak of a new coronavirus in China, authorities said Tuesday, as more places stepped up medical screening of travelers from the country as it enters its busiest travel period.

The increased control measures followed a sharp rise in the number of infections to more than 200 people since last month, with epidemiologists still uncertain of its nature and mode of transmission.

Chinese health authorities confirmed late Monday that some cases had been transmitted person-to-person, a development that means the illness could spread faster and more widely, particularly at the start of the Lunar New Year travel rush. Click here for more. 

Biden accepts Sanders's apology over unofficial surrogate’s blistering op-ed.
AOC declares Democrats a 'center-conservative' party.
Super Bowl LIV will feature 49ers coach Katie Sowers' historic appearance.

Macron tweets he and Trump reach truce on taxing tech companies.
Boeing's 737 Max jet crisis has company seeking loans: report.
Here are the most and least educated states in America.
#TheFlashback: CLICK HERE to find out what happened on "This Day in History."

Tucker Carlson warns President Trump and Republicans not to get overconfident about the 2020 election.

Not signed up yet for Fox News First? Click here to find out what you're missing.

Click here to find out what's on Fox News and Fox News Radio today!
Fox News First is compiled by Fox News' Bryan Robinson. Thank you for making us your first choice in the morning! Enjoy your day! We'll see you in your inbox first thing Wednesday morning.