Indiana Gov. Mike Pence said Wednesday that Donald Trump would make good on his promise to build a wall on the southwestern U.S. border, but told voters to "stay tuned" to Trump's upcoming immigration speech to hear other aspects of Trump's plan.

Pence said in a radio interview that Trump would "very quickly" deport illegal immigrants who commit crimes once he is president. But he left wiggle room on what to do with millions of other illegal immigrants already in the country. That uncertainty comes as Trump has indicated a change in tone from the campaign on whether all 11 million illegal immigrants should be deported.

"Donald Trump should be commended for putting the issue of illegal immigration front and center in this election year when it had, for many politicians, faded to the back," Pence said. "And, look, he's made it very, very clear. He's been very consistent. We're going to have secure borders. We're going to build a wall. We're going to enforce the laws of this country and do so vigorously."

"Individuals who have committed crimes in this country are going to go, and they're going to go very quickly to be processed for a justice system and out of this country," Pence said. "Beyond that, I just think, stay tuned. Another one of these major speeches is coming up, Donald Trump will address the issue of immigration. I guarantee you he's going to be a man of his word."

"Securing our borders, enforcing our laws and whatever else we do will be tough but fair, and it will reflect the kind of compassion and humanity the American people would expect and, frankly, that proceeds out of this good man," he added.

Trump was initially slated to deliver his immigration speech on Thursday in Colorado, but the campaign postponed that address to do some fine-tuning. The decision came after a report emerged over the weekend which suggested that Trump has started to soften his rhetoric on the issue, though he pushed back against chatter that he was flip-flopping.

Campaign manager Kellyanne Conway blasted reports of Trump softening on immigration. Conway argued that Trump is just trying to get a handle on what is "such a complex issue."