Donald Trump will make a surprise trip to Mexico to meet the country's president hours before delivering a highly-anticipated speech on immigration.
The Republican White House candidate said on Twitter that he looks "very much forward" to meeting President Enrique Pena Nieto.
The Mexican leader had invited both Mr Trump and his Democrat rival Hillary Clinton to visit Mexico.
Mr Pena Nieto and Mr Trump will meet in private on Wednesday.
Mr Trump has made illegal immigration and his call for a wall along the US-Mexico border a centrepiece of his presidential campaign.
Mr Pena Nieto has been sharply critical of Mr Trump's insistence that Mexico would pay for the border wall.
In an interview in March, he said that "there is no scenario" under which Mexico would do so.
He also compared Mr Trump's language to that of dictators Adolf Hitler and Benito Mussolini, saying it had hurt US-Mexico relations.
But he used a different tone late on Tuesday, writing on Twitter: "I believe in dialogue to promote Mexico's interests in the world and, principally, to protect Mexicans wherever they are."
In recent meetings with Hispanic supporters, Mr Trump has suggested he could be open to changing the hardline approach on immigration he outlined during the Republican primaries.
The tycoon did not mention the Mexico trip during an evening rally outside Seattle, but he did make a reference to his scheduled speech on immigration that is set for Wednesday evening in Phoenix.
"We are also going to secure our border and stop the drugs from pouring in and destroying our country," he said.
"And I'll be talking about that tomorrow night in Arizona. Big speech on immigration. We'll be talking about that in Arizona tomorrow night."
