President Donald Trump's personal assistant, John McEntee, was fired Monday and escorted out of the White House amid a Secret Service investigation into serious financial crimes, NBC News reported Tuesday. He has now joined Trump's re-election campaign as a senior advisor. Trump 2016 campaign spokeswoman Katrina Pierson is also joining the 2020 re-election campaign as a senior advisor. "Katrina and John will play pivotal roles on our campaign once again as we develop a winning strategy through 2020 to Keep America Great," said Michael Glassner, the campaign's chief operating officer. "They will also contribute tremendously to our national engagement in the mid-term elections this year. We're delighted to have them back on the team."

John McEntee walks to Marine One to join U.S. President Donald Trump for travel to Florida in Washington, February 16, 2018. Leah Millis | Reuters

McEntee, who served on Trump's winning presidential campaign beginning in 2015, joined the Trump administration after the election. He was escorted off the White House grounds on Monday over an "unspecified security issue," the Wall Street Journal first reported, citing sources. Federal law enforcement officials later confirmed to NBC that McEntee was under investigation by the Secret Service for serious financial crimes. The Wall Street Journal reported that McEntee had problems relating to gambling and taxes that were an obstacle to his obtaining security clearance. The news of McEntee's firing came just minutes after reports that Secretary of State Rex Tillerson had been booted after more than a year as the top U.S. diplomat.