US President Donald Trump said he was dropping – for now – his push to deploy National Guard troops in Chicago, Los Angeles and Portland, Oregon, after legal roadblocks held up the effort.

“We will come back, perhaps in a much different and stronger form, when crime begins to soar again – Only a question of time!" he said in a social media post on Wednesday.

Governors typically control their states' National Guardsmen, and Trump had deployed troops to all three cities against the wishes of state and local Democratic leaders. He said it was necessary as part of a broader crackdown on immigration, crime and protests.

He has made a crackdown on crime in cities a centerpiece of his second term – and toyed with the idea of invoking the Insurrection Act to stop his opponents from using the courts to block his plans. He has said he sees his tough-on-crime approach as a winning political issue ahead of next year’s midterm elections.

Trump’s push to deploy the troops in Democrat-led cities has been met with legal challenges at nearly every turn. The Supreme Court in December refused to allow his administration to deploy National Guard troops in the Chicago area. The order was not a final ruling but was a significant and rare setback by the highest court for the president’s efforts.

Illinois governor JB Pritzker wrote on X Wednesday that Trump “lost in court when Illinois stood up against his attempt to militarize American cities with the National Guard. Now Trump is forced to stand down”.

Hundreds of troops from California and Oregon were deployed to Portland, but a federal judge barred them from going on the streets. A judge permanently blocked the deployment of National Guard troops there in November after a three-day trial.

Oregon governor Tina Kotek said on Wednesday that her office had not yet received “official notification that the remaining federalized Oregon National Guard troops can return home. They were never lawfully deployed to Portland and there was no need for their presence. If President Trump has finally chosen to follow court orders and demobilize our troops, that’s a big win for Oregonians and for the rule of law”.

Trump's decision to federalise National Guard troops began in Los Angeles in June, when protesters took to the streets in response to a blitz of immigration arrests in the area. (AP)