Trump stands firm on wall while wavering on its type

US PRESIDENT Donald Trump has pledged not to bend in his demand for a wall along the southern border with Mexico but said the barrier could be made of steel instead of concrete as a potential compromise with Democrats who refuse to fund it.

Mr Trump’s comments came at the start of the third week of a partial government shutdown resulting from the dispute that has left hundreds of thousands of federal workers idle or without pay.

Mr Trump threatened again, without providing specifics on where the funding would originate, to declare a national emergency as an alternative way to build the wall, depending on the outcome of talks in the coming days.

Democrats have declined to approve the $US5.6 billion ($A7.9 billion) for the wall. Mr Trump wants to fulfil a 2016 campaign promise to curb illegal immigration. Led by new Speaker Nancy Pelosi, Democrats passed a bill in the House of Representatives last week to reopen the government without wall funding. Ms Pelosi has called a border wall immoral.

“This is a very important battle to win from the standpoint of safety, number one, (and) defining our country and who we are,” Mr Trump told reporters at the White House before leaving for Camp David.

“The barrier, or the wall, can be of steel instead of concrete, if that helps people. It may be better.”