US President Donald Trump signed a sweeping tax and spending bill into law on Friday, a day after Congress narrowly passed it.

It makes his 2017 tax cuts permanent, slashes federal spending on federal safety-net programs, and funds a major expansion of border security and defense.

"I've never seen people so happy in our country because of that, because so many different groups of people are being taken care of: the military, civilians of all types, jobs of all types," Trump said at the signing ceremony during a Fourth of July picnic at the White House.

It passed the House by just four votes, with nearly all Democrats and two Republicans opposing over concerns about health care cuts and a projected $3 trillion (€2.5 trillion) increase to the national debt.

 'One Big Beautiful Bill' could add trillions to US debt

After a hard-fought legislative process, Trump achieved his goal of signing the signature policy bill on US Independence Day.

"America's winning, winning, winning like never before," Trump said.

He thanked the Republican lawmakers who helped pass the bill in Congress, especially House Speaker Mike Johnson who was on hand to witness the signing.

The bill, dubbed the "One Big Beautiful Bill Act," calls for tax breaks and increases in defense spending and immigration enforcement.

"So you have the biggest tax cut, the biggest spending cut, the largest border security investment in American history," Trump said.

At the same time, it will shrink the federal food assistance program and force through the largest cuts to the Medicaid health insurance scheme for low-income Americans since its 1960s launch.

According to some estimates, up to 17 million people could lose their insurance coverage under the bill.

Analysis by the nonpartisan Congressional Budget Office also suggests it will add more than $3 trillion to the nation's $36.2 trillion debt.

Democrats see the legislation as key to their battle for control of Congress

Democratic National Committee Chair Ken Martin said in a statement that Trump's signature on the legislation "sealed the fate of the Republican Party, cementing them as the party for billionaires and special interests — not working families."

He predicted the law would cost Republicans votes in next year's congressional elections in 2026.

"This legislation will hang around the necks of the GOP for years to come," he said.

Democrats are rolling out an ambitious campaign of rallies, voter registration drives, attack ads, bus tours, and even a multiday vigil, aimed at spotlighting the most controversial aspects of the legislation.

"This was a full betrayal of the American people," Martin said.

Edited by: Srinivas Mazumdaru