Pollster says Trump's approval rating in 2020 will be impacted by Dem nominee

Pollster Mike Greenfield told Hill.TV on Wednesday that President TrumpDonald John TrumpTrump cites tax cuts over judges as having biggest impact of his presidency Trump cites tax cuts over judges as having biggest impact of his presidency Ocasio-Cortez claps back at Trump after he cites her in tweet rejecting impeachment MORE's approval rating going into 2020 will likely depend on the popularity of his future Democratic opponent. 

"It's going to matter who the Democrat is," Greenfield, the CEO and co-founder of Change Research, told host Jamal Simmons on "What America's Thinking." 

"We're seeing in early polling that [Joe] Biden does a little bit better than other candidates, and obviously that still has to be fleshed out," he continued. 

"People don't know a lot of the other candidates, but it does matter who the Democrat is," he said. 

A new Hill-HarrisX survey, released on Wednesday, showed the president's approval at 46 percent. 

An Emerson College survey, released last month, showed former Vice President Biden beating Trump in a hypothetical race by 10 points. Biden is expected to announce his run later this month.

The survey also showed Sen. Kamala HarrisKamala Devi HarrisBiden calls for equal pay for US women's soccer team Biden calls for equal pay for US women's soccer team Confused by polls? Watch early primary states — not national numbers MORE (D-Calif.) beating Trump by four points, while Sens. Elizabeth Warren (D-Mass.) and Bernie Sanders (I-Vt.) each edge Trump by 2 points. 

— Julia Manchester