WATCH LIVE: Trump to give remarks on immigration
US President Donald Trump signals denuclearization talks with North Korean leader Kim Jong Un remain alive, nearly two weeks after cancelling a trip to Pyongyang by Secretary of State Mike Pompeo. (AFP / NICHOLAS KAMM)

Trump has ramped up his tough stance on illegal immigration, an issue that appeals to his core supporters, before elections on Tuesday that will determine whether his fellow Republicans keep control of Congress.

He will deliver brief remarks at the White House at 4:15 p.m. ET (2015 GMT) on “the illegal immigration crisis and give an update on border security, White House Press Secretary Sarah Sanders said in a statement.

In recent days, Trump has sought to present as a threat to the United States a large group of migrants from Central America who have left poverty and violence at home and are heading slowly through Mexico toward the U.S. border.

Republican Senator Chuck Grassley, an ally of the president and head of the powerful Senate Judiciary Committee, echoed some of the Republican president’s strong rhetoric about the caravan in a letter to the secretaries of the Department of Homeland Security and the State Department.

In the letter, Grassley said his office had received information that several members of the caravan had “significant criminal histories” and was seeking information about “potential national security threats that reportedly exist among the members.”

Trump said on Wednesday that the United States could send as many as 15,000 troops to the border to confront the migrant caravan, more than twice the number previously disclosed by defense officials.

Republican lawmakers and other Trump supporters have applauded the deployment. But critics argue Trump has manufactured a crisis to drive Republican voters to the polls.

On another immigration front, Trump said this week he would seek to scrap the constitutional right of citizenship for U.S.-born children of noncitizens and illegal immigrants, saying he would issue an executive order on so-called birthright citizenship.

Trump and some other Republicans say the right - granted by the Constitution’s 14th Amendment - creates an incentive for people to enter the country illegally to have children. But critics, including some other Republicans, say the president cannot change the constitution by fiat. Such an action would virtually guarantee a legal challenge.