Activists widely expected Joe Biden to take swift action against the death penalty as the first sitting president to oppose capital punishment, especially since an unprecedented spate of executions by his predecessor ended just days before he took office.

Instead, the White House has been mostly silent.

Mr Biden hasn’t said whether he’d back a bill introduced by fellow Democrats to strike the death penalty from US statutes. He also hasn’t rescinded Trump-era protocols enabling federal executions to resume and allowing prisons to use firing squads if necessary, something many thought he’d do on day one.

And this week, his administration asked the Supreme Court to reinstate the Boston Marathon bomber’s original death sentence.

The hands-off approach in Washington is adding to disarray around the death penalty nationwide as pressure increases in some conservative states to find ways to continue executions amid shortages of the lethal-injection drugs.

Worse, some longtime death penalty observers say, is that Mr Biden’s silence risks sending a message that he’s OK with states adopting alternative execution methods.

“Biden’s lack of action is unconscionable,” said Ashley Kincaid Eve, a lawyer and activist who protested outside the Terre Haute, Indiana, prison where the federal inmates were executed.

“This is the easiest campaign promise to keep, and the fact he refuses to keep it is political cowardice.” His cautious approach shows the practical and political difficulties of ending or truncating capital punishment after it’s been integral to the US criminal justice system for centuries, even as popular support for it among both Democrats and Republicans wanes.

Mr Biden didn’t make capital punishment a prominent feature of his presidential run, but he did say on his campaign website that he would work “to pass legislation to eliminate the death penalty at the federal level, and incentivise states to follow the federal government’s example”.

That simple-sounding promise was historic because it wasn’t just about the federal death penalty, which, before former President Donald Trump, had been carried out just three times in the previous five decades.

Then, 13 federal prisoners were executed during Trump’s last six months in office during the height of the coronavirus pandemic. Mr Biden’s promise also took direct aim at states, which, combined, have executed some 1,500 inmates since the 1970s; 27 states still have death penalty laws.

But the fact that the administration chose to actively push for Dzhokhar Tsarnaev execution suggests the president’s opposition to the death penalty isn’t as all-inclusive as many activists believed.

However, Abe Bonowitz, director of anti-capital punishment group Death Penalty Action, said he and other activists have spoken with administration officials and received some behind-the-scenes assurances Mr Biden will eventually back legislation to abolish the federal death penalty.