Marking Labour Day in the US, president Barack Obama signed an executive order providing up to seven days-a-year of paid sick leave to contractors who work for the federal government.
The order, enacted by Obama independently of Congress, will benefit an estimated 300,000 workers who don't currently receive paid leave.
Under the ruling, employees on federal contracts will be entitled to a minimum of one hour paid leave for every 30 hours they work.
Employees will also be allowed to use the leave to care for sick relatives.
The change will come into effect from 2017.
"Unfortunately, only Congress has the power to give this security to all Americans, but where I can act, I will," the president told the Greater Boston Labour Council's Labour Day Breakfast in Boston.
The White House estimated that 44 million workers in the private sector, about 40 per cent of the workforce, don't have paid sick leave.
The measure is the latest White House order to help workers.
In February 2014, Mr Obama signed an order raising the minimum wage for government contractors to $10.10 an hour (about €9.05).
He introduced another in July 2014 banning federal contractors from discriminating against employees on the basis of sexual orientation or gender identity.
In Boston, Mr Obama chastised Republicans for policies of cutting taxes for the richest Americans and loosening regulations.
Mr Obama said that the party thinks that “you look up at the sky and prosperity will come raining down from whatever high-rise is in your city.
“That’s not how the economy works.”
Without naming them, Mr Obama ridiculed New Jersey governor Chris Christie, a Republican presidential candidate, for saying that a teachers' union deserved a punch in the face, and Wisconsin governor Scott Walker, another candidate, for saying that busting unions in his state prepared him to fight Islamic State militants in the Middle East.
“I didn’t make that up. That is what he said,” the president said.
Defending the protections afforded to workers by trade unions, Mr Obama pointed to how the NFL Players Association last week won a court action overturning a four-game suspension for New England Patriots quarterback Tom Brady for colluding with team members to deflate footballs below the permitted limit during a playoff game.
“Even Brady’s happy he’s got a union,” said Mr Obama, to laughs and applause in Boston.
“They had his back. So if Brady needs a union, we definitely need unions.”