Leading Democrats demanded the Trump administration act to curb white nationalists following the worst attack on Latinos in US history.

The US president was accused of stoking up the hatred with his rhetoric, including his vitriolic attack on four ethnic minority congresswomen last month.

It was this climate, Democrats said, which culminated in the carnage at a shopping mall in El Paso, Texas leaving 20 dead and 26 injured, of whom three are reported to be in a critical condition.

Attention focused to the threat posed by the far-right following the discovery a lengthy racist manifesto reportedly left by Patrick Crusius, 21, from Allen in Dallas Texas, the man named by US media outlets as suspected of being responsible for the slaughter.

District Attorney, Jaime Esparza, said that he would seek the death penalty for the suspect. John Bash, the US Attorney said the mass shooting was being treated as a domestic terrorism case.

The El Paso massacre was the third high profile attack linked to the far right in less than five years.