Donald Trump Tours U.S.-Mexico Border

Presidential candidate Donald Trump faced questions about immigration policy from reporters Thursday at the U.S.-Mexico border amid roiling controversy about his bombastic style and his controversial remarks about Mexican immigrants.

He did not respond to a question from NBC News regarding what he plans to do about the nation's estimated 11 million undocumented immigrants.

"First thing we have to do is strengthen our borders and after that we'll have plenty of time to talk about it," he said.

Asked if his tour of the border yielded any evidence to support his claim that Mexico is "sending criminals" over the border, Trump promised to produce documentation but offered no details.

"We'll be showing you the evidence," he said, declining to elaborate.

Trump, who told Washington D.C. newspaper The Hill in an interview that he would consider running as an independent if he didn't feel the Republican Party was "fair" to him, did not reiterate that threat when speaking with reporters in Laredo.

"I want to run as a Republican. I think I’ll get the nomination, we’ll see soon enough," he said. "The best way to win is for me to get the nomination and run against probably Hillary [Clinton]."

Trump landed in heavily Hispanic Laredo, TX, with scores of media on hand to witness the descent of his private plane, emblazoned with Trump's name.

He went forward with the trip despite a last-minute revocation of an invitation from a local border patrol union that initially offered to host the real estate tycoon's tour of the border.

In a statement Thursday morning, National Border Patrol Council Local 2455 said: "After careful consideration of all the factors involved in this event and communicating with members of the National Border Patrol Council (NBPC) at the National level, it has been decided by Local 2455 to pull out of all events involving Donald Trump."

Trump's campaign blamed the move on the union's national leadership.

"It is unfortunate the local union of Border Patrol Agents received pressure at a national level not to participate and ultimately pulled out of today's event. They are being silenced, and are very unhappy about it, as told directly to Mr. Trump," the campaign said.

Trump has been under fire for characterizing Mexican immigrants as "rapists" and "criminals" when he announced his presidential run last month.