US President Donald Trump said on Friday he can now push through a raft of controversial policies, after the country's Supreme Court handed him a "giant win" by curbing the ability of lone judges to block his powers nationwide.

In a 6-3 ruling stemming from Trump's bid to end birthright citizenship, the court said nationwide injunctions issued by individual district court judges likely exceed their authority.

"This was a tremendous win," Trump told reporters in a hastily arranged press conference at the White House. "I want to just thank again the Supreme Court for this ruling."

Trump said he would now proceed with "so many policies" that had been "wrongly" blocked, including his bid to end birthright citizenship, and stop funding for transgender people and "sanctuary cities" for migrants.

Democrats swiftly blasted the decision, saying it would embolden Trump as he pushes the boundaries of presidential power in his second term.

Senate Democratic Leader Chuck Schumer called it a "terrifying step toward authoritarianism".

"This is really the opposite of that," Trump argued. "This really brings back the Constitution".

The Supreme Court did not rule on the constitutionality of Trump's executive order seeking to end automatic citizenship for children born on US soil.

But the broader decision on the scope of judicial rulings removes a big roadblock to Trump's often highly contested policy agenda and has far-reaching ramifications for the ability of the judiciary to rein in Trump or future US presidents. (AFP)