U.S. President Donald Trump urged Congress on Tuesday to give him 5.7 billion U.S. dollars this year to help build a wall on the border with Mexico, but stopped short of declaring a national emergency that could have led to unilaterally funding the project.

Facing Democratic opposition in Congress to a wall, Trump said in a prime-time televised speech that there was a growing security crisis at the U.S.-Mexico border.

He cited figures to make a point about the damage illegal immigration has caused to America, saying the country is facing a "crisis of the heart" and "the crisis of the soul".

In the speech, Trump also blamed the partial government shutdown on Democrats, saying it is caused by "one reason only", that is the Democrats will not fund border security.

He framed the struggle on whether or not to pass his spending bill, which includes the fund for the wall, as a choice between right and wrong, and that between justice and injustice.

But after days of hinting that he might use his presidential powers to declare an emergency as a first step toward directing money for the wall without congressional approval, Trump appeared to be willing instead to continue seeking a solution to the impasse with Congress.

"Pass the bill and end the crisis." Trump urged.

In response, Democratic leaders Nancy Pelosi and Chucker Schumer delivered rebuttals minutes after Trump's address, blaming the U.S. President for the partial government shutdown. 

House Speaker Pelosi noted that Trump had rejected bipartisan legislation to reopen the government agencies shuttered as a result of the fight over the wall.

"President Trump must stop holding the American people hostage, must stop manufacturing a crisis and must reopen the government," she said. 

House minority leader Schumer called on the president to separate the shutdown from the argument about border security, end the shutdown while allowing the debate to continue. 

Trump is scheduled to visit the southwest border on Thursday and it was not clear whether he still might choose to make the national emergency declaration.

Trump's remarks came 18 days into a partial government shutdown precipitated by his demand for wall construction, which he has said is needed to keep out illegal immigrants and drugs.

Opposition from Democrats 

Democrats and other opponents of the border wall had threatened to take legal action if Trump issued the emergency declaration.

They say he is using false claims and manufacturing a crisis to carry out his 2016 presidential campaign promise for a wall that he said at the time would be paid for by Mexico.

The Mexican government has refused to provide such funds.

Hoping to demonstrate flexibility during his nearly 10-minute speech on Tuesday evening from the White House Oval Office, Trump said of the border barrier he wants to build: "At the request of the Democrats it will be a steel barrier and not a concrete wall."

But Democrats have opposed not just the construction materials to be used, but the extent of a project that could end up costing more than $24 billion over the long run.

Democrats also argue that a mix of fencing, which already has been constructed in many parts of the border, and higher-tech tools would be cheaper and more effective in securing the border.