Donald Trump says he will close down the US government if necessary to build his wall along the Mexico border.
The president told supporters at a "Make America Great Again" rally in Phoenix, Arizona, that the opposition Democrats were being "obstructionist".
During the 80-minute speech, he also took aim at the media, blaming them for giving far right groups "a platform".
But he selectively quoted his initial response to violence at a far-right rally that left one woman dead.
He omitted the much-criticised claim that "many sides" had to shoulder the blame for violence in Charlottesville, Virginia.
What did he say about the wall?
President Trump wants Congress to finance his controversial plan to build a "big, beautiful" wall along the United States' border with Mexico to keep out illegal immigrants.
But Republicans will need the support of Democrats to secure funding for the wall in a government spending bill, which they are unlikely to get.
In his speech, Mr Trump said the Democrats were "putting all of America's safety at risk" by opposing the wall. He said immigration officers who worked in the area said it was "vital" to stem the flow of illegal immigrants.
Six things that could topple Trump's wall
What Trump's rally taught us
He said that, if it came to it, he would risk a government shutdown - which is what happens when legislation funding the federal government cannot be passed by Congress and non-essential services stop.
"Now the obstructionist Democrats would like us not to do it, but believe me if we have to close down our government, we are building that wall," Mr Trump said, adding that "the American people voted for immigration control".
If President Trump wants a government shutdown all he has to do is refuse to sign a funding bill sent to him by Congress.
Capitol Hill is set to debate a new budget measure this autumn, and unless it is passed federal operations will be in limbo by 1 October
