The 2020 election is still over 1,000 days away, but President Trump is already floating, and ruling out, possible challengers, Politico reports. "He's always asking people, 'Who do you think is going to run against me?'" said one aide who has personally heard such musings.

Two of the Democratic Party's most high-profile potential candidates, Vermont Sen. Bernie Sanders and Massachusetts Sen. Elizabeth Warren, don't cause Trump to break a sweat, Politico notes. Despite Sanders being rated as the most popular politician in the country by several polls last year, and Public Policy Polling predicting in July that he could beat Trump by 13 points in a head-to-head general election, Trump dismissed Sanders, 76, as being too old to run again. Warren would also be "easy to beat," Trump has reportedly said, and his team is similarly unconcerned about Sen. Kirsten Gillibrand (D-N.Y.).

"If the Democrats think a socialist or a liberal professor from Massachusetts are a path to victory, we're happy to help them highlight that, because we don't think that is in tune with the vast majority of Americans," a Republican National Committee spokeswoman said. Sen. Kamala Harris (D-Calif.), another potential 2020 candidate, was not on Trump's "radar yet," Politico notes.

Trump hasn't ruled out every potential challenger, though. His team is reportedly concerned about former Vice President Joe Biden, fellow billionaire Mark Cuban — and Oprah Winfrey. "Oprah would be a problem," a Republican strategist told Politico. "She'd be their best. She's ubiquitous, she's black, she has crossover appeal, and she probably clears a lot of the field out." Jeva Lange