(CNN) - Massachusetts Democratic Sen. Elizabeth Warren and Vermont independent Sen. Bernie Sanders met Wednesday night as speculation about their plans for the 2020 presidential election heats up, a source familiar with the meeting said.
Only the two senators were at the meeting at Warren's condominium in Washington, according to The New York Times, which was first to report the meeting. Citing two Democrats briefed on their discussion, the Times reported the senators told each other they are seriously considering running for president in 2020.
The source familiar with the meeting told CNN it's "not surprising" that the two would meet, considering their closeness as Senate allies and their respective political ambitions.
Some on the left are concerned that two high-profile progressives running against each other would take away from each other's support, which could lead to a less progressive candidate winning the nomination, according to the Times.
"When it comes to progressives, I think Bernie and Warren are in a different league," California Democratic Rep. Ro Khanna told the Times. He said, "I'll have to decide" who to support if both senators run, according to the Times.
A Sanders spokesman did not respond to multiple requests from CNN for comment, and Warren spokespeople declined to comment to CNN.
Last week, The Boston Globe -- Warren's hometown paper -- published an editorial saying the paper's editorial board was "skeptical" of a Warren 2020 run and that the Massachusetts senator had "missed her moment in 2016." Warren has been heavily criticized for her decision to release a DNA test in October to prove her Native American heritage after President Donald Trump repeatedly attacked her and nicknamed her "Pocahontas."
Sanders said in November that he will "probably run" if he thinks he is the best candidate to beat Trump in 2020.
"If there's somebody else who appears who can, for whatever reason, do a better job than me, I'll work my ass off to elect him or her," the Vermont independent said in an interview with New York Magazine. But, Sanders told the magazine, "if it turns out that I am the best candidate to beat Donald Trump, then I will probably run."
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