Beto O’Rourke may have inadvertently got the ball rolling this week on an emerging litmus test for Democrats eyeing the White House in 2020 when he said he “absolutely” supports tearing down the existing barriers along the southern border with Mexico.

Since then, the other Democrats eyeing the 2020 Democratic nomination are facing calls to say whether they agree. And some are now expressing an openness to it, as they work to appeal to a liberal base that argues the wall is immoral.

“Curious to know if @KamalaHarris, @CoryBooker, @ewarren, @JulianCastro, @gillibrandny and @amyklobuchar agree with @BetoORourke that we should tear down the wall that already exists at the border?” tweeted Brad Parscale, Trump’s re-election campaign manager.

O’Rourke, the former Texas Democratic congressman and potential presidential candidate, called for the destruction of the El Paso wall after the White House said President Trump would declare a national state of emergency to fund the remainder of his border wall project.

During an interview in his hometown on Thursday, MSNBC host Chris Hayes asked O'Rourke: "If you could, would you take the wall down here -- knock it down?"

BETO SAYS HE 'ABSOLUTELY' SUPPORTS DESTROYING EXISTING WALLS ON SOUTHERN BORDER

"Yes, absolutely," answered O'Rourke, who is widely thought to be a potential candidate in 2020 but has not formally announced his intention to run. "I'd take the wall down."

And on Friday, at least one Democrat in the 2020 field signaled they are open to it.

GILLIBRAND ON CALL TO TEAR DOWN BORDER WALL: 'IF IT MAKES SENSE, I COULD SUPPORT IT'

"I could look at it and see which part he means and why and if it makes sense I could support it,” New York Sen. Kirsten Gillibrand told Fox News in New Hampshire on Friday.

Meanwhile, Republicans expressed disbelief over O’Rourke’s comments, while signaling they believe they could use the issue to paint Democrats as extreme and pro-open borders.

“Correct me if I am wrong, but did Beto say he would tear down existing border fencing and walls?” tweeted Texas Sen. John Cornyn, who is up for re-election in 2020. Some Democrats have encouraged O’Rourke to challenge Cornyn if he doesn’t run for president.

“Give Beto O’Rourke points for honesty: he admits that he wants to tear down existing border walls & have totally open borders,” said Arkansas Republican Sen. Tom Cotton. “At least he’ll say what most Democrat politicians believe.”

RNC chairwoman Ronna McDaniel used O’Rourke’s comments to say it’s proof Democrats are “the party of open borders.”

While O’Rourke was the first likely 2020 presidential candidate to call for tearing down walls, other lesser-known Democrats in recent weeks have suggested they support the idea.

In an interview in January for example, Democratic Texas Rep. Veronica Escobar told CNN that "we know walls don't work, that they don't stop drugs, that they don't stop migration." Escobar also suggested she was open to destroying existing walls, remarking that they are "really ugly" and "monuments to division."

HOYER SAYS BORDER WALLS 'OBVIOUSLY' WORK, REJECTS PELOSI'S SUGGESTION THAT BARRIER IS 'IMMORALITY'

But not all Democrats have embraced the idea: House Majority Leader Steny Hoyer, D-Md., said during an interview on Fox News' "Special Report with Bret Baier" last month that border walls "obviously" work in some areas, and he rejected suggestions that barriers should be removed where they already exist.

Fox News’ Gregg Re contributed to this report.