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Developing now, Monday, April 1, 2019

TRUMP: NO MORE PLAYING 'NICE' AT THE BORDER - President Trump has threatened to shut down the southern border this week to combat the illegal immigration crisis and in a tweet sent Sunday night, he suggested he was done playing Mr. Nice Guy ... "The Democrats are allowing a ridiculous asylum system and major loopholes to remain as a mainstay of our immigration system," Trump tweeted. "Mexico is likewise doing NOTHING, a very bad combination for our Country. Homeland Security is being sooo very nice, but not for long!"

Meanwhile, Trump has also vowed to cut direct aid to El Salvador, Guatemala and Honduras as their citizens flee north toward the U.S. in caravans. Mexican officials said Sunday they will give out humanitarian visas on a "limited basis" to some of the roughly 2,500 Central American and Caribbean migrants gathered in the southern state of Chiapas.

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2020 DEMS 'BELIEVE' BIDEN'S ACCUSER: A number of Democratic presidential candidates weighed in over the weekend on the allegations made by a former Nevada political candidate that former Vice President Joe Biden inappropriately touched and kissed her on the back of the head during a 2014 campaign rally ... Sen. Amy Klobuchar, D-Minn., told ABC's "This Week" that she has no reason not to believe the allegations made by Lucky Flores. Sen. Bernie Sanders, I-Vt., who is running for the Democratic nomination, said during an interview with CBS' "Face the Nation” that while he has no reason not to believe Flores, he doesn’t believe that “one incident alone” would disqualify Biden from running for the White House. On NBC's "Meet The Press, former Colorado Gov. John Hickenlooper called the allegations against Biden "very disconcerting."

Earlier in the weekend, while speaking to reporters in Iowa, Sen. Elizabeth Warren, D-Mass., and former Housing and Urban Development Secretary Julian Castro said they believed Flores. Biden – who is expected to soon launch his 2020 presidential bid – has denied ever acting inappropriately toward Flores or anyone, but promised to "listen respectfully"

Wife of former Defense secretary calls photo with Biden misleading

Lara Trump on O'Rourke: 'He's a great skateboarder ... We don't worry about Beto.'

ICYMI: TIME FOR A HISTORY LESSON FOR AOC? - Rep. Alexandria Ocasio-Cortez, D-N.Y., might want to brush up on some history after asserting, incorrectly, that Republicans in Congress amended the Constitution to kick President Franklin Delano Roosevelt out of office ... "They had to amend the Constitution of the United States to make sure Roosevelt did not get reelected," Ocasio-Cortez said Friday during a night hall event with MSNBC with Chris Hayes. Ocasio-Cortez was referring to the 22nd Amendment of the Constitution, which passed in 1947. FDR died in office in 1945.

FAIRFAX ACCUSER SPEAKS OUT: One of the two women accusing Virginia Lt. Gov. Justin Fairfax of sexual assault has spoken out publically on television for the first time, saying that she wants to testify in front the Virginia Assembly -- and that Fairfax should resign ... Vanessa Tyson, an associate professor of political science at Scripps College in Claremont, Calif., told "CBS This Morning" in an interview airing on Monday that she did not want her students interested in politics to face a similar situation. CBS News' interview with Fairfax's other accuser, Meredith Watson, is set to air Tuesday. A spokesperson for Fairfax said Sunday the lieutenant governor had taken two polygraph tests showing that he engaged in "no wrongdoing whatsoever."

SLAIN STUDENT'S LAST MOMENTS CAPTURED ON CHILLING VIDEO: Authorities on Sunday released surveillance video they said showed the moment a University of South Carolina student exited a bar and entered the car she mistakenly thought was her Uber, but was instead her alleged killer ... Samantha Josephson, 21, could be seen approaching the Chevy Impala and entering the backseat. Columbia Police Chief Skip Holbrook said investigators found the victim’s blood in Nathaniel David Rowland’s vehicle. Rowland is in custody, charged with kidnapping and murder.

THE SOUNDBITE

'CREEPY UNCLE JOE' - "If anybody just types in 'Creepy Uncle Joe Videos' you come up with a treasure trove. I think Joe Biden has a big problem here because he calls it affection and handshakes, his party calls it completely inappropriate.” – Kellyanne Conway, counselor to President Trump, on "Fox News Sunday," on the allegations of inappropriate conduct leveled against former Vice President Joe Biden by former Nevada political candidate Lucky Flores. (Click the image above to watch the full video.)

TODAY'S MUST-READS

Report: Trump 'saving' Judge Amy Coney Barrett to replace Ginsburg.

Why didn’t Obama do more to counter Russia’s interference in our election?

Nipsey Hussle, Grammy-nominated rapper, shot dead in Los Angeles.

MINDING YOUR BUSINESS

Facebook's Zuckerberg calls for more regulation of Internet.

What happens if the Trump administration kills ObamaCare?

Bait crisis could take the steam out of lobster this summer.

STAY TUNED

On Fox News:

Fox & Friends, 6 a.m. ET: Special guests include: Tom Homan, former acting director of U.S. Immigration and Customs Enforcement (ICE). "Unplanned" star Ashley Bratcher explains why she fired back at Alyssa Milano's attack on Georgia's pro-life bill. "Catch a Contractor" host Skip Bedell kicks off "Fox & Friends'" spring cleaning series with do-it-yourself tips.

Hannity, 9 p.m. ET: Special guests include Karl Rove, former White House deputy chief of staff under President George W. Bush, and Victor Davis Hanson, author of "The Case for Trump."

Fox News @ Night, 11 p.m. ET: Ken Starr, former Whitewater independent counsel

On Fox Business:

Mornings with Maria, 6 a.m. ET: Special guests include: U.S. Rep. Dan Meuser, R-Pa.

Varney & Co., 9 a.m. ET: Brandon Judd, National Border Patrol Council president.

Countdown to the Closing Bell with Liz Claman, 3 p.m. ET: Former Department of Homeland Security Secretary Jeh Johnson.

After the Bell, 4 p.m. ET: Atish Davda, founder and CEO of EquityZen.

On Fox News Radio:

The Fox News Rundown podcast: "The Border May Be Closing" - Fox News' Claudia Cowan has an update at the southern border from El Paso, Texas as President Trump threatens to shut down the border. An interview with writer, director, actor Terry Gilliam on his new film, "The Man Who Killed Don Quixote." Plus, commentary by Guy Benson, co-host of "Benson & Harf."

Want the Fox News Rundown sent straight to your mobile device? Subscribe through Apple Podcasts, Google Play, and Stitcher.

The Brian Kilmeade Show, 9 a.m. ET: President Trump's threat to shut down the southern border, the Mueller report and the latest in the 2020 presidential race will be the topics of debate with the following guests: Michael Goodwin, New York Post columnist; Karl Rove, former White House deputy chief of staff under President George W. Bush; Adm. James Stavridis, operating executive with The Carlyle Group; Bret Baier, host of "Special Report"; Corey Lewandowski, former Trump campaign manager.

The Todd Starnes Show, Noon ET: Todd speaks with Trump campaign adviser Lara Trump and U.S. Sen. Marsha Blackburn, R-Tenn., about President Trump’s plan for the border and James Dobson Family Institute founder Dr. James Dobson will discuss his organization’s latest victory in the name of religious freedom.

#TheFlashback

2003: American troops enter a hospital in Nasiriyah, Iraq, and rescue Army Pfc. Jessica Lynch, who had been held prisoner since her unit was ambushed on March 23.

1984: Marvin Gaye is shot to death by his father, Marvin Gay, Sr. in Los Angeles, the day before the recording star's 45th birthday. (The elder Gay would plead guilty to voluntary manslaughter, and receive probation.)

1976: Apple Computer is founded by Steve Jobs, Steve Wozniak and Ronald Wayne.

1954: The United States Air Force Academy is established by President Dwight D. Eisenhower.

Fox News First is compiled by Fox News' Bryan Robinson. Thank you for joining us! Have a good Monday (and don't fall for April Fools' jokes)! We'll see you in your inbox first thing Tuesday morning.