Image copyright Getty Images Image caption Beto O'Rourke (left) and Elizabeth Warren (right) have criticised fellow 2020 candidate Joe Biden over his stance on the Hyde Amendment

Former US Vice-President Joe Biden is under fire from fellow 2020 Democratic presidential candidates for his stance on abortion.

Elizabeth Warren and Beto O'Rourke are the latest contenders to attack Mr Biden for supporting a law that bars federal abortion funding.

Other Democratic hopefuls fired off thinly veiled criticisms of him.

Mr Biden is currently front-runner in the race for his party's nomination in next year's presidential election.

He has long voiced support for the Hyde Amendment - a law passed in 1976, right on the heels of the Roe v Wade Supreme Court ruling that legalised abortion across the US.

His campaign told NBC News this week he was still in favour of the amendment, triggering a backlash from liberal Democrats.

What is the Hyde Amendment?

In 1976, Henry Hyde, an Illinois Republican congressman, wrote an amendment to a federal funding bill that stated: "None of the funds contained in this Act shall be used to perform abortions except where the life of the mother would be endangered if the foetus were carried to term."

The amendment meant that the vast majority of women receiving federal assistance through the low-income healthcare programme Medicaid would be blocked from using that money for abortion services, which can often cost several hundred dollars.

In 1994, under Democratic President Bill Clinton, the Hyde Amendment was updated to include exceptions in cases of rape or incest.

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What did O'Rourke and Warren say?

On Wednesday, both Mr O'Rourke, a former Texas congressman, and Ms Warren, a Massachusetts senator, directly criticised Mr Biden's stance.

Speaking to MSNBC during a televised town hall event, Ms Warren said she felt Mr Biden was wrong to support the amendment because "it's just discrimination".

She said the law disproportionately impacts poorer women.

Mr O'Rourke told CBS News that Mr Biden's viewpoint was "absolutely wrong".

"Perhaps he doesn't understand," he said, "who the Hyde Amendment hurts the most, lower income communities, communities of colour."

Mr Biden is a practising Roman Catholic who has previously said he personally opposes abortion, but does not think he should impose his religious beliefs on others.

The debate over repealing the Hyde Amendment is one of those instances where the political drama outweighs any real-world implications.

The Hyde Amendment has been on the books in the US for more than 40 years. The prohibition on taxpayer-funded abortions is unlikely to disappear anytime soon, whether or not a Democratic presidential candidate supports it.

What repeal advocacy demonstrates to some Democrats, however, is an entirely different issue. Joe Biden, for much of his early career, opposed legalised abortion. And while he's shifted on that issue, his continued backing of the Hyde Amendment is a vestige of his very long political trail.

Now that abortion rights have been put at risk by state-level legislation and face an uncertain future in the US Supreme Court, Mr Biden's views open him to attack from competitors seeking to tarnishing his front-runner status.

The criticisms could damage the former vice-president among the activist base of the Democratic Party. The former vice-president, however, has claimed a lead in opinion surveys based on the backing of politically and socially moderate Democrats, who may - like Mr Biden - have complicated views on abortion.

Their continued support is worth more to Mr Biden than any endorsements from abortion-rights groups.

Media playback is unsupported on your device Media caption The abortion battle explained in three minutes

What about the other 2020 candidates?

The four female senators running for the 2020 Democratic presidential nomination - Ms Warren, Kamala Harris, Kirsten Gillibrand and Amy Klobuchar - have co-sponsored a measure to revoke the Hyde Amendment.

They fired off criticisms of the law this week on Twitter, without directly naming Mr Biden.

Others among the field of 24 candidates for the 2020 Democratic nomination - including Bernie Sanders, Cory Booker and Jay Inslee - have expressed support this week for repealing the law.